Beware The Nice Ones / Anime & Manga

What happens when you take an innocent, gentle child with untapped power and enrage him beyond all measure.

Examples of Beware the Nice Ones in Anime and Manga.

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• Belldandy from Ah! My Goddess is a prime candidate, with her always presenting a quiet and gentle personality. Because she has such incredible self-control and such a kind personality, she's given access to more power than anyone else in the series, with the exception of Hild (and the Almighty, but he doesn't appear).
  • When her self control slips, nearby glass shatters and pipes burst. Seeing a pattern, Urd exploits Belldandy's jealousy, which makes Belldandy subconsciously create an explosion so powerful it defeats Garm, who outclassed Urd.
  • When they're at the hot springs with the demon Mara, Belldandy lays down a rule against fighting. "And if you break it, I will punish you." Urd and Mara are understandably unnerved.
  • And God save your soul if you dare to hurt Keiichi. She's scary enough when she's just disappointed in your actions... this will flat-out make her angry. The first time this happens in the manga, she does not hesitate to unleash her "Holy Wind Press", an attack spell, on his assailants (a brainwashed Tamiya and Otaki), a sight which absolutely terrifies Skuld.
  • She is shown to be an excellent fighter who has a Valkyrie license. She just doesn't like to fight.
  • Seriously, Bell-chan is a rather bossy girl by nature. Her sisters are even a little afraid of her. She is just really, REALLY good at covering it up with her gentle facade. If she wanted, she could make Keiichi do absolutely anything. Thank the almighty she's the nicest person you will ever meet.
  • Speaking of Valkyries, Lind is a polite and proper girl with the kind of decorum you would expect of an Officer and a Gentleman. Her job description? Heaven's Own One-Woman Army.
• Assassination Classroom:
  • Nagisa Shiota is a nice kid who gets along with everyone in the Ragtag Bunch of Misfits that is class 3-E, and is even a vegetarian to boot. But on the other hand, everyone acknowledges that he's the single best assassin in the classroom; his stealth and sheer bloodlust can make elite veteran soldiers shit bricks. He's not violent or anything, he just has no compunction against killing people. But if you make him get violent? There was only one person in the series who seriously and directly provoked Nagisa, and it was a mistake that left him traumatized for the rest of his life.
  • Koro-sensei applies as well. No matter how close you come to killing him, the worst he'll do is be a relentless troll and/or clean and groom the would-be killer. But get someone else hurt in the process? Then he'll remind you that he chooses to be passive instead of the planet-destroying monster that he is. Or rather, instead of the world's greatest assassin that he used to be.
• Asteroid in Love: When Sayuri lets slip her willingness to blackmail the Earth Science Club in exchange for a scoop, Mari records the conversation and uses it to blackmail her instead.
• Hanji Zoe from Attack on Titan comes across as extremely cheerful and eccentric, being one of the most friendly senior officers in the Survey Corps. Though something of a Nightmare Fetishist when it comes to Titans, it really is easy to forget that Hanji is a veteran soldier in the branch with the highest mortality rate and not someone to make angry. Though slow to anger, Hanji shows no mercy once provoked — dangling a priest 50 meters off the ground to interrogate him and on another occasion, calmly preparing to engage in a bit of Cold-Blooded Torture against a captured enemy.
  • Armin Arlert may be physically the weakest among the trainees and since childhood constantly depended upon Mikasa and Eren to protect him, but he's also a tactical genius who can quickly deduce his enemies' weaknesses and has no qualms about exploiting them. His taunt to Bertholt about how Annie was being tortured to make him lose focus was both genius and disturbing.
• Baki Hanma from Baki the Grappler is generally a good-natured Nice Guy, but he can become a dangerous force to be reckoned with whenever he is angered or if the people he cares about are in danger.
• Yoshitoki Kuninobu in Battle Royale is usually a very mild-mannered, almost shy guy. But as Shuuya says in his narration, and as Kinpatsu Sakamochi/Yonemi Kamon (depending on which medium one experiences Battle Royale in) finds out, he will turn into a berserker when someone close to him is harmed. Case in point, when Sakamochi/Kamon revealed that he raped — or in some versions, killed — Miss Ryoko, the woman that has taken care of him and Shuuya since childhood, Yoshitoki went insane, screaming that he'll fucking kill him, and rushed at him. Yoshitoki ends up killed before he can do anything.
• Leo Aoi of Beast Master. Despite his scary face, he's as sweet as a guy can be, but when he sees blood, or God forbid, you try to hurt Yuiko, he will kill you if Yuiko doesn't stop him in time.
• Grell Sutcliff from Black Butler. Through most of the Jack the Ripper arc, he's the quiet/suicidal/klutzy butler of Madame Red who more or less functions as comic relief through his epic failure at his work. Until you catch him, of course. Then he pulls a grin that can be nightmare-inducing at best, proceeds to change his appearance dramatically and turns into a chainsaw-wielding psychopath that is very forward about his creepy attraction to Sebastian, within the same five minutes talking about both wanting to cut him into pieces and bearing his child. It's revealed that he's a shinigami gone pseudo-rogue and has been half of Jack the Ripper, allowing Madame Red to commit her crimes without being noticed. The useless butler routine was just to keep suspicion off him. He helps Madame Red kill the prostitutes because it's a distraction and he's bored with sticking to his list; it's also speculated that, as an okama, Grell shares Madame Red's frustrations about being unable to give birth.
  • Then there are the servants of the Phantomhive family, klutzy, bumbling, carefree, and happy. Then the circus comes to town and we learn why they have the jobs they do.
    • Especially Finnian in the manga, the last person you would expect to perform a cold, grisly murder while his friends watch in horror.
• In Black Lagoon, Rock is by far the nicest person you will find... but if you push him TOO far, particularly by wantonly abusing an innocent girl he was trying to help, he will show you that he is just as dangerous as his crewmates. This is after all the guy who took out an airborne helicopter with a torpedo. And flicked off the helicopter as it exploded.
  • And the female employees of the Lovelace Family are also not to be trifled with, despite their demure and deferential exteriors. ESPECIALLY Roberta. Lay a finger on the Young Master and she will kill you. Repeatedly. With a .50 caliber sniper rifle, ONE-HANDED.
• Bleach:
  • Captain Retsu Unohana. A motherly Yamato Nadeshiko type in charge of a company full of healers, one look from her can scare anyone. Even people who don't scare easily such as Kenpachi Zaraki. We later find out that this is very justified: she is the First Kenpachi and creator of the 11th Division. She named herself "Yachiru" to reflect the fact she's a Master Swordsman and was the most diabolical criminal in Soul Society history before she became The Atoner.
  • Gentle Giant Hachigen Ushoda manages to stay calm and polite even when he reveals himself to be pure badass.
  • Handsome Gentle Giant Chad who refuses to harm even bullies, but don't ever threaten his friends.
  • Hachi Ushoda of the Visored is a very good natured, kind-hearted subservient sort who is so uncombative his specialty in combat is barrier magic. He's also the only one of the Visored to land a killing blow against a Arrancar. That Arrancar being Barrigan, second strongest of them all. With just barrier magic.
• Blue Exorcist:
  • Okumura Rin. Nice? Yes, though a bit rough around the edges. He's friendly, loyal, an amazing cook, and The Heart of the team. He's also the Son of Satan. Which means if you anger him enough, he will destroy you with his Super-Strength and Hellfire. Luckily there are only a few ways to piss him off; unfortunately, that includes hurting his friends or little brother, little things that seem to be a hazard of being an exorcist...
  • And then Moriyama Shiemi nearly out-matches him. She's one of the kindest and most sensitive of the group, being previously sheltered. She's also the most powerful second to Rin, capable of delivering a Curb-Stomp Battle to a powerful demon aka she used it as fertilizer with the help of her familiar to create a giant tree that also busted her out of the trap.
• In Brave10, Rokuro is Yukimura's taciturn page^*whenever he's not nagging Yukimura, that is who's always serving tea, and doesn't look like much of a fighter. He's also the Team Mom—but that only means the other Braves have learned first-hand what happens when you piss your mom off. It usually involves blackouts and nausea.
• Bungo Stray Dogs has Kenji, who is a gentle and polite country boy, who happens to possess Super-Strength under regular circumstances. When he actually gets angry, that strength becomes akin to a natural disaster.
• There's no doubt that Aoi of Castle Town Dandelion is an extremely nice girl^note as in, one that doesn't ruin the world by Compelling Voice despite without the knowledge of having such power.. But when Hikari is starting to tell Akane that the populace knew Scarlet Bloom is Akane all along in Chapter 21/Episode 9A, Aoi asked Hikari to "talk for a minute"... in a way that Hikari came out with a Thousand-Yard Stare.
• In Cannon Busters, Sam is a cute Cloud Cuckoolander Robot Girl who's programmed for friendship and wants to be friends with everyone she meets. But if she sees you threatening someone she's identified as a friend, she undergoes a One-Winged Angel transformation into a monsterous warbot and obliterates you with a Wave-Motion Gun.
• Cardcaptor Sakura: Sakura is cheerful and caring, but the Snow Card will forever remember what happens if she gets REALLY angry... During the fight Sakura loses the wristwatch Yukito gave her as a birthday present, and since she had a crush on him this really angers her. One-Hit Kill with the Fire Card. Shaoran got really scared at that.
• Case Closed:
  • Toyed with in Okiya Subaru, a friendly Sherlock Holmes-loving grad student living in Conan/Shinichi's house who also gives Haibara/Sherry the chills, which only happens around Black Organization members. Most likely it's just a "friends close, enemies closer" plan. Subverted when it turns out to be Akai Shuuichi in disguise as part of his and Conan's plans.
  • Conan's excuse for letting the fox-faced Subaru stay at his house: "A person who loves Sherlock Holmes couldn't possibly be evil!"
• Cells at Work! features the White Blood Cells, who are generally amiable guys when you get to know them. Threaten the body, however, and they turn into bloodthirsty Seeker White Blood Cells that think of nothing but your grisly demise.
• Change 123: The female protagonist, Motoko Gettou, is a double instance. If you mess with her, you get beaten up by one of her split personalities, of which there are three (named "Hibiki", "Fujiko", and "Mikiri", collectively known as "HiFuMi"); each with its own individual conscience and each as badass as the next. Assuming you somehow manage to beat those, enjoy it while it lasts; you'll be dead in a moment by the vastly more powerful Superpowered Evil Side that is the fifth personality named "Zero" (as in, she came first before the other three), the embodiment of all her rage and hatred (the Tranquil Fury kind, hence her dead-eyed emotionless expression and near silence), whom none of the other alter egos even knew about until she first debuted in-story (and only two other people had prior knowledge of her — three if you count Kannami deducing her existence in-story). Worse yet, after Zero's existence was revealed to Motoko and HiFuMi, any time someone pushes HiFuMi to the Rage Breaking Point and none of the personalities are able to defeat the enemy, the personality that's still in control will temporarily merge with Zero' and attain her absurd power and lack of regard for human life (other than Kosukegawa's, that is). Just pray that Kosukegawa manages to snap her out of it in time to save your sorry life.
• Chrono of Chrono Crusade is a Adorably Precocious Child that often gives speeches about The Power of Friendship and behaves politely even to people that don't trust him because he's a demon. But he is a demon, and when his powers are unsealed he turns into his true form—a bishounen powerhouse with massive amounts of power. When he gets really angry, he's been known to fly into Unstoppable Rage fits with little thought to any collateral damage that may occur.
• Code Geass's Princess Euphemia doesn't count since her genocidal rampage was caused by Geass and not any of her own pent-up aggression, but shy little fangirl Nina Einstein certainly does. She's almost perfectly normal, aside from her deep-seated fear of Japanese people and her rather obvious crush on Princess Euphemia, who intervened to save her from Japanese terrorists. When Euphinator was killed by Zero, though, she promptly turns a previous offhand mention of her technical skill in a prior episode into building a hybrid nuclear/sakuradite bomb that causes an instant stalemate between Britannia and the Black Knights, as it's theoretically powerful enough to destroy all of the Tokyo Settlement if she triggers it, which the emotionally distraught girl is perfectly willing to do just for a chance to kill Zero.
  • A running gag among certain circles is that the sweetest, most innocent character, Nunnally Lamperouge, actually hides a horrible dark side◊ that will surface if she ever gets a Geass of her own or indeed regains sight.
    • Considering what happens in the Nightmare of Nunnally Alternate Universe manga and what happened in Episode 22 of R2, the possibility is out there.
  • Suzaku definitely counts, though. He's an all-around Nice Guy who just wants peace, but will destroy pretty much anyone who threatens to upset the current peace. After the Euphemia example above, it just gets worse, since he outright stops being nice.
    • Suzaku is a bit of a deconstruction because he was Hot-Blooded in his childhood to begin with. As pleasant as he can be in the present, his current drive for peace, though, is just part of a death wish from killing his father seven years earlier. Once the Euphemia example happens as mentioned, it's little surprise that his old bitter headstrong habits resurface.
  • Lelouch is a questionable one. He WAS a Nice Guy, but then his mother died, his sister was maimed, and his family abandoned him. By the time he walks through a village of shredded bodies, "nice" is just a mask he remembers how to wear.
    • He still does have a degree of kindness that roots itself in his desire to change the world, but there's no question that this series involves a great deal of his own catharsis. Even so, you can't deny he still did manage to show how much he was really holding back once he passes the Despair Event Horizon.
• Spike from Cowboy Bebop is apparently just a lanky carefree dude with a very zen attitude to life, fairly friendly and good-hearted. What he isn't telling you is that he's a master martial artist and gunslinger supreme, and the reason he's so zen is because he considers himself already dead, so he never holds back. Annoy him enough and he'll beat you senseless without breaking a sweat. Harm someone he loves and he'll return the favour tenfold. Kill someone he loves and he'll annihilate an entire army to get to you and then kill you, even if it costs him his life.
• Anime.Daltanious: Sanae is an Actual Pacifist that hates violence so much she offers herself as a punching bag to Danji if it means he won't attack the thirves that stole her kimono. And even she isn't above reprimanding Kento for his bratty behaviour.
• Dance in the Vampire Bund: Do not mess with the fangless—vampires who willingly pulled out their fangs to preserve their humanity—because having the weaknesses of/being hated by both vampires and humans made them the best guerrilla fighting force on the planet. For example, when a powerful vampire clan raided the Bund and started rounding them up, the fangless responded by leading the main force into a tight hallway filled with Razor Floss and dropping their entire apartment complex on the rest.
• In Dangaioh, an ex Ordinary High-School Student is The Leader of the group that pilots the huge Super Robot that gives its name to the series. Why? Because Miya Alice is capable of unleashing ENORMOUS Psychic Powers once she's mad, frightened, or determined to fight and protect her partners: Roll, Pai and Lamda.
• Machiya from DEAD Tube is a quiet, nice and introverted person, happy with being the Cameraman of the Film Research Club lead by his beloved Senpai, his reaction to the first DEAD Tube event is of shock, but his sexual arousal towards it shows he isn’t really innocent; when the Film Research Club is revealed to be part of DEAD Tube and has been lying to Machiya all this time, the guy manages to trick them before said revelation, even when all signs pointed towards he being completely played like a fiddle.
• In the last episode of Death Note, Matsuda, by far the nicest, gentlest character in the entire show, seems to suffer a Heroic BSoD when Light finally reveals himself to be Kira after years of having put his complete faith in Light's innocence, but when Light tries to use a piece of the notebook to quickly write Near's name, Matsuda immediately shoots the pen out of his hand. He angrily asks Light what his father even died for if the murderer he was trying to catch was his own son who led him to his death, but Light just calls his father a fool and tries to goad Matsuda into killing everyone in the room so his death won't be in vain. When Matsuda doesn't fall for it, Light tries one more time to kill Near, and Matsuda completely snaps, shooting Light four more times, and he would have put the last bullet between his eyes if the rest of the task force hadn't grabbed him at the last second.
  Matsuda: I'll kill him. I'LL KILL HIM! HE HAS TO DIE!
• Shimada from Death Parade. He is a sweet and polite young man who cared deeply for his sister Sae and did whatever it takes to protect her after their parents died. If you ever say anything bad about Sae or even go as far as assault her, there will be hell to pay. He will go as far as murdering the culprits and, given the opportunity, torture them and watch as they suffer as excruciatingly as possible.
• DEVILMAN crybaby: Akira Fudo is a very nice guy even after his transformation, so long as you are not a demon. However, even kind and compassionate Akira has his limits. The mob that kills Miki and his friends learn this the hard way when Akira uses his powers to incinerate them.
• D.Gray-Man: Allen Walker is a cheerful, kind young man who loves everyone, and has made it his mission to not only save humanity, but also release akuma-captured souls from their pain and suffering. But do NOT get him angry, because he will make the offender very, VERY sorry.
  • General Tiedoll is probably an even straighter example. He has one of the most ridiculously powerful Innonences so far (being able to manipulate nature, including making mile-high white wooden Humongous Mechas and creating a city-sized anti-akuma blast without actually harming the city), is a skilled artist and treats younger Exorcists like sons (to the point where he teared up when he thought Kanda wasn't gonna return from the Ark in time). We have yet to actually see him angry, which makes the above mentioned feats even scarier.
• In Digimon Adventure, Gabumon is probably the gentlest and sweetest-natured of the original 7 Digimon partners. However, pose even the remotest threat to Matt (even if you ARE Matt) and he will show you just how dangerous a wolf he can be. Case in point: Remember when I said "even if you're Matt"? Well, when Matt started sinking into depression late in the show, Gabumon took it upon himself to pull him out of it...by BITING the kid!
• In Digimon Adventure 02, Takeru/T.K. is normally a nice guy, unless you happen to be meddling in the powers of darkness, or trying (and failing) to whip him senseless, leading to a Megaton Punch in return.
  • Hikari/Kari doesn't tend to get angry, but do not kill her friends. Vamdemon/Myotismon and Mugendramon/Machinedramon both made this mistake. In both cases, it was the last mistake they would ever make. Subverted, though, in that both of them barely survived and later returned in One-Winged Angel forms, which returned yet again after they were defeated the second time.
• In Digimon Tamers, Takato is the least Hot-Blooded out of all the goggle boys of the series. Guilmon was this by default (naïve, yet a powerful fighter, voiced by Masako Nozawa—remind you of anyone on this page?), but Takato snaps when Beelzemon kills Leomon permanently...he was already not willing to forgive Beelzemon right before that moment, but what happens next is reminiscent of Adventure. Takato made WarGrowlmon turn into his 'natural' final stage - the EMBODIMENT OF APOCALYPSE ITSELF, an abomination whose mere existence was a hazard to the integrity of both worlds, through sheer anger alone. He then sent it to EAT his opponent.
• In Digimon Ghost Game, we have Gammamon, a cute, friendly and generally childlike Digimon, and while he is willing to fight, he generally aligns with his partner Hiro on most subjects. But if Gammamon is pushed too far, that's when very bad things happen, because it turns out, A monster on par with Megidramon (the monster described in the Tamers section) also inhabits Gammamon's body (or rather, the Gammamon known to the heroes was an alternate personality that somehow became the main personality). And worse, unlike the Tamers example, this other entity is smart, cunning and dreadfully sadistic. Naturally, if Gammamon is pushed too far, this other being takes over, and the results are never pretty: Even Hiro himself is not safe from the Jet-Black Champion's wrath, as made abundantly clear in Episode 66.
• Dorei Shouni Shika Sentakushi Ga Nai Desu Yo: The first time the protagonist, Zeolith, got angry, due to the murder of a girl he liked, he tracked down the criminal mastermind, forced her goons to brutally kill each other, and then ripped out the soul of the woman who was the mastermind and shoved the soul of the murder victim into her body not caring a whit about what happened to the Alpha Bitch afterwards.
• Dragon Ball Z:
  • Gohan, throughout most of the series, is a pacifist who abhors violence, but when provoked (namely by hurting his loved ones, or just any Innocent Bystander for that matter), can fly into a near psychotic rage and suddenly increase his strength to colossal heights. Through this he was the first to unleash the devastating power of a Super Saiyan 2, which also turned him from the kindhearted boy he is into a sadistic homicidal monster with the power to decimate entire Solar Systems!
  • Goku, even when fighting seriously to avenge fallen comrades or save the world, maintains a constant sunny disposition and childlike naïveté throughout the series, allowing for humor in otherwise climactic battles. Goku only completely snaps when Frieza mercilessly kills his lifelong friend Krillin, and then threatens to do the very same thing to his son. His first transformation into a Super Saiyan turns him into a cold, taunting, ruthless and arrogant fighter who starts to beat Frieza to within an inch of his life. It wasn't the first time either — when Krillin is murdered by one of Piccolo's minions, Goku takes off in a blind rage swearing bloody revenge. This side of Goku returns in Dragon Ball Super when Zamasu reveals that, in an alternate timeline, he murdered Chi-chi and Goten in cold blood after stealing his body and again when Jiren attempted to nuke the stands holding the remaining members of Universe 7. He got so angry that he actively tried to kill Black without mercy.
  • Future Trunks would fit this trope well. He's normally a quiet and polite guy, but growing up in a Bad Future turned him into the most merciless of all of the Z fighters. He won't even think twice about slicing his enemies to bits and turning them into dust, as he did to Frieza. King Cold was grievously wounded and literally begging for his life when Trunks just straight-up executed him. Heck, for the sake of preventing the nightmare from happening again, he won't hesitate to blast anyone, up to and including his own father, Vegeta.
  • Beerus exemplifies this: his typical demeanor is polite and easy-going. Beware, however, for he has a Hair-Trigger Temper who will blow his stack at the most petty and inconsequential of slights, which tends to go very poorly for everyone around him, being the God of Destruction and all.
    • Whis is Beerus' Angel and general caretaker. He doesn't have Beerus' Hair-Trigger Temper, snarks at Beerus every chance he gets to set him off, and is friendly, agreeable, personable and kind. He's also more powerful than Beerus is and knows it meaning he's capable of beating Beerus in single combat. Yes an angel has power that trumps a god of destruction.
  • Beerus's boss Zen'o is generally friendly and even-keeled, and quickly befriends Goku when the latter proves not to be afraid of him. He's also much more powerful than Beerus, and capable of destroying the entire multiverse when properly motivated. And that's no Informed Ability- he does so to Future Trunks' timeline to get rid of Infinite Zamasu, who'd merged with it. There's a reason why him just showing up terrifies Beerus and Champa.
    • He's also arguably the most disturbing example, as he still smiles cheerfully while doing that, and it's unclear if he even understands the implications of obliterating beings as thoroughly as he does.
• Shizuo Heiwajima is a quiet yet somewhat shy and awkward young man who hates violence. But when he gets pissed (which is alarmingly often), look out.

E-H

• Elfen Lied:
  • Lucy's first major massacre was a textbook example of a Beware the Nice Ones snap-out: As a child, she lived at an orphanage where the other kids were absolutely cruel, tormenting and harassing her for her "cute little horns" and seemingly emotionless nature. They finally pushed Lucy too far when she started caring for a puppy and they forced her to watch as they kicked it around and beat it to death with a vase, just to get her to show something. Lucy unleashed her diclonius powers for the first time, leaving no witnesses.
  • Nana has plenty of this as well. While normally one of the kindest, sweetest characters in the entire series, there are very rare occasions where she slips into a stoic, death-glaring persona that is utterly serious and tranquilly furious. Bandou is the first to be on the receiving end of this side of her, and only a grazing blow to her head saves his life. In the manga only, she gets two more moments, both brought about by threats against her loved ones; Mariko threatening Nana's "papa" (who, unknown to both of them, is Mariko's biological father, but that's another story) sends Nana into this state of mind, letting her thrash the previously-undefeated Mariko, and when the Unknown Man threatens to rape Mayu (with whom Nana is very close) and reveals how he horribly mutilated and killed a captive Diclonius, Nana is fully ready to kill him before he hits her with a nerve-toxin ball that leaves her unconscious from pain. Long story short: Nana is, most of the time, infinitely more pleasant and kind than Lucy, but do not push her to the breaking point and do not threaten her loved ones.
• Gentle Giant Kurita in Eyeshield 21 is probably the nicest, friendliest character in the entire series. He is also the main linesman of the Deimon Devilbats and he will crush you to protect his team. In fact, his strength increases the more people he has to protect.
  • Sena (initially) is a complete doormat who will run your errands and allow himself to be bullied into doing things. But insulting his friends is one thing he will not stand for because he will destroy you.
• Fairy Tail: Mirajane is usually calm, friendly and a non-action member of the guild. But if you have anything to do with someone she cares about facing potential danger, this trope starts to manifest in her "demon" glare. And when someone nearly kills her younger brother, she activates her Satan Soul transformation and savagely tramples her opponent. Just about everybody in the entire guild has at least shades of this trope, but it's most pronounced in Mirajane because she's ordinarily extremely sweet and kind to everyone she meets.
  • Oddly enough, Mavis qualifies. Friendly, sweet, and Not So Above It All in regards to the guild... but then she comes face to face with Zeref, someone she apparently has a history with, and responds to his threat of being an Omnicidal Maniac with a flat-out death threat, something that is otherwise a big no-no in Fairy Tail, as well as legal guilds in general.
• Youichi from Father and Son is a nice father towards Shou (when he's not causing mischief), but anytime his son goes too far or if someone upsets him, he will get angry. It certainly doesn't help that he used to be a gangster in his youth.
• Food Wars!: Downplayed because it's a cooking manga, but Satoshi Isshiki definitely qualifies. He's unfailingly friendly and polite to pretty much everyone, and unlike other members of the Council of Ten masters he's very humble and doesn't like to rub his status on other people's faces. He's also a Cool Big Bro to the other residents of the Polar Star Dormitory, to the point that insulting them is the one thing that will genuinely make him angry, as Julio Shiratsu found out the hard way during the Regimental Shokugeki when he called them "riffraff".
• Chiffon Fairchild of Freezing. One of the very few sane people among a student body of blood knights, she is the number one rank not only in her school, but across a world-wide network of schools... with the moniker of "Unmatched Smiling Monster". Uh...
• Fruits Basket:
  • Kagura Sohma is usually a cute, sweet girl with a cheerful disposition, but she actually shows her love for Kyo by beating him to a pulp on sight, especially if he refuses her advances. This frequently leads to Shigure's house being broken. When they were both little kids, apparently she got Kyo to propose to her by threatening him with a knife (or a big rock in the anime).
  • Hatsuharu Sohma is usually kind, if eccentric and a little out of it, but when he snaps he turns into "Black Haru", a bloodthirsty version of himself with a whole lot of attitude. When he finds out about Akito's abuse of Rin, he's so outraged that he pins Akito to a wall and nearly punches them out, leaving them stunned and wide-eyed; this is made all the more impressive when one recalls that, as Akito is God of the Zodiac, Haru shouldn't even be able to stand up to them, let alone physically assault them, due to the curse.
  • Tohru Honda herself is an All-Loving Hero, kind, polite, and sweet to everyone even if they don't return her kindness, but she will not hesitate to protect her friends and those she loves. When Akito threatens to lock up and torture a terrified Yuki for defying them, Tohru intervenes and shoves them away from him.
• Fullmetal Alchemist:
  • For the most part, Major Alex-Louis Armstrong is a Large Ham Gentle Giant. Emotionally scarred by the idea of killing civilians, always trying to give his opponents the chance of surrendering, had a terrible Heroic BSoD during the Massacre of Ishbal, etc... Then a homunculus goes and tries to kill his older sister, and so he kills it until it dies.
  • Alphonse is a Gentle Giant who wouldn't hurt a fly, but he has come close to flying into a merciless rage (and does a few times in Fullmetal Alchemist (2003) on multiple occasions. You do not want to mess with those he cares about. Seriously, DON'T. If his older brother Ed can't beat him in a fight, you won't.
  Alphonse: Mr. Tucker... If you keep talking, this time I'LL shut you up.
• In Full Metal Panic? Fumoffu, there is a janitor who is known to be very kind to anyone. He stays gentle when Sousuke and the Karate club leader destroy a big part of the school attempting to help, but when they serve him a dish, a fish named Catherine whom he considered a daughter, he attempts to kill them with a chainsaw, and proves to be Nigh-Invulnerable, by being shot many times with a shotgun and some grenades without any ill effects.
• Galaxy Fraulein Yuna's title character: sweet, bubbly, loves making friends with everyone she meets, whether they started out hostile or not. If you value your continued existence, absolutely do not kill any of her friends. Beating them up but letting them survive is apparently okay, but Genmu crossed the line and paid for it.
• Weed of Ginga Densetsu Weed is a very pure, sweet and small adolescent Akita/Kishu mix, but he proves to be one of the best fighters in the series. When a packmate defies his orders and kills two of his enemies against his wishes, he bites the dog, who is a powerful German shepherd by the way, on the neck and tosses him away. He also holds his own against a Great Dane that dwarfs him, talking advantage of his speed and his ability to perform the Battōga, a attack that came from wolves. Being the grandson of Japan's greatest bearhound pays off.
• Rushuna of Grenadier is a sweet Ms. Fanservice whose goal is to get people to stop fighting by the power of her smile. When that doesn't work, she pulls out her six-shooter and blasts anything that moves. A castle full of riflemen led by an armored giant wielding a machine gun, who won't release the helpless prisoner?
  Rushuna: "You don't get a smile!" (she proceeds to shoot EVERYONE)
• Henrietta in Gunslinger Girl is as cute as a button... until an assault on her beloved handler Giuseppe brings back subconscious memories of her own childhood trauma. Then she proceeds to kill everyone in sight.
  • Actually, the organization that Henrietta is a part of is basically built on this trope, with a small battalion of cute, dormant psychopaths, including one who continually keeps a Limit Break saved up until she ends up being kidnapped in place of the bad guys' actual target. Yeah... that didn't go so well.
• Subaru from .hack//SIGN is about the most likeable character in the show. Then in comes the GIFT Affectionate Parody OVA where she poleaxes Ginkan for disregarding her orders so brutally that Censor Steam is employed in the scene (implying that it wouldn't be appropriate even for 17+ audiences).
• Hakaiou Noritaka! has Hotei: a quiet and nice guy who happens to practice full contact karate, always trying the diplomatic way first and even letting Noritaka go when he accidentally defaces and destroys the Karate Club's sign (as it had been an accident)... But if one manages to get him angry, they find out the hard way why his nickname is "human weapon", with his Establishing Character Moment ending with Yamakawa of the Judo Club, who had previously insulted all other combat sport and Hotei had caught molesting a girl, having to be hospitalized with eight broken bones (including his left knee)... And not only Hotei was going easy to try and make him apologize, he wasn't finished when Noritaka distracted him long enough to calm down.
• Kamijou Maki from Hayate × Blade is perhaps the most notable example in her series. For almost 6 volumes, the readers hardly ever see her making an appearance for more than a couple of pages (which was even lampshaded in a side story), and when they do, she's portrayed as a whipped, mild-mannered, low-profile dork. Then one opponent breaks her right arm. Her response? "The judges can't stop me here. How lucky."
• Ikaros from Heaven's Lost Property. She is a sweet and caring girl, even if she is most powerful weapon ever made. You would never expect her to hurt anyone, until her master is in danger. There was also one time in which she completely lost her mind when she was granted freedom and nearly killed her former master, until he agreed to become her owner again.
• Seras Victoria from Hellsing seems to start off as a sort of as a Wide-Eyed Idealist until the Valentines' attack on the Hellsing base sends her into an Unstoppable Rage which you might think hails from her vampiric nature. However, a detailed look into Seras "Kitten" Victoria's history reveals she's had a vicious temper as far back as her childhood in an orphanage when she brutalized a fellow orphan who was bullying and tormenting her, and that she's been actively keeping that violent part of herself in check since long before becoming a vampire. Zorin Blitz gets nailed with both barrels of this trope when she makes the mistake of pushing Seras too far with her cruelty, culminating in Seras reducing Zorin's face into a bloody smear against the wall after fully awakening into a vampire.
• In Hetalia: Axis Powers, Hungary, the cute young girl who was Austria's maid and later advisor before marrying him, will not hesitate to invoke her massive fighting skills (which she acquired when she was a pint-sized warrior girl) and maul you if you hurt her husband (Well, she might hesitate if you're a cute male and you're molesting him. And not always, mind you. You're warned, France)
  • And Lithuania? That nice guy? Quite a good spy and fighter who won't hesitate to put a knife to your neck if your threaten someone he cares for, specially his old friend Poland. You're warned, Prussia.
    • As a rule, everyone in the Baltic/Soviet region is a case of Beware the Nice Ones. Even the Shrinking Violet little brother of Lithuania, Latvia... Having a Psychopathic Manchild as your boss leaves marks on you, indeed.
  • As a child, Italy at one point completely kicked Turkey's ass. Turkey's 'I really hate kids' says it all.
  • If you make the sweet Meganekko Canada lose his patience, you'll find yourself on the receiving end of a hilarious yet absolutely epic "The Reason You Suck" Speech. If America couldn't get his brother off his back for three hours straight, then so won't you.
  • Remember Finland? Sweden's "w'f"? Finland with the adorably off naming skills and the food preferences of a pregnant rat on acid? Well, while it's not shown in the strips just yet, plenty of fanfic has explored why it's probably best not to forget.
    • His partner Sweden is a Gentle Giant of few words who dotes on his "w'f", but in the aftermath of the April Fools' Day, it's him who thinks of the punishment for France.
  • Ukraine is a sweet Team Mom and Prone to Tears... who will subtly manipulate her very scary younger siblings to get what she wants from them and will hold her ground if she has to.
  • Belgium is shown to be a rather Nice Girl prone to Heroic Self-Deprecation, but her profile refers to her as being scary when she's mad. The fact that she has a rifle and looks like she knows how to use it indicate that this probably would not be a good thing.
• Higurashi: When They Cry:
  • Rika herself notes, regarding the main cast, that, "They are all caring, gentle individuals. And yet, once the wheels of fate go awry, they become controlled by delusion and start committing deadly acts of violence." Considering how much this anime seems to enjoy breaking cuties, this shouldn't come as a surprise.
  • In the end however, the Big Bad plotting all the terrible occurrences turns out to be an apparent Nice One as well, even if she (Miyo Takano) looks half-stoned at all times, moonlights as a nurse, and apparently dies early into every cycle.
  • More so. Her Start of Darkness shown in last arc, reveals that Takano is in fact a broken cutie. While she was a nice young child... having her parents die and then getting sent off to a particularly monstrous Orphanage of Fear leads her to angrily defy god.
• Rika from His and Her Circumstances is, for the most part, a quiet, unassuming girl. But when she was a kindergartener, Rika found out that Kyo, an older boy who usually looked after her, was getting picked on, she saved Kyo from the high school bully by bashing him with a baseball bat. She really must have done a number on the guy, as she had blood splatter on her face.
• In His Favorite Satou has the mask of a indulgent popular guy, but if Yoshida says something about you that makes him jealous, you'd better have a good excuse. Poor Yamanaka.
• Sora of How to Keep a Mummy is one of the nicest folks around. He is often compared to a Doting Parent in his care of the tiny mummy Mii-kun. However, when someone up and steals Mii-kun, Sora's anger is such that even his best friend from childhood, known for a sadistic streak of his own, is legitimately scared of him.
• Gon from Hunter × Hunter. Cute, lovable, Gon... don't hurt or threaten any of his True Companions. Seriously, don't. He's scarier than Killua when pissed, and capable of terrifying some of the most powerful beings in the world, with Pitou even thinking that with his Nen empowered by rage Gon might even become a threat to the Chimera Ant King.

I-M

• I'm Gonna Be an Angel!:
  • Mikael is usually an epitome of calmness, kindness and politeness when dealing with strangers and people he's not close to, unless he's with Raphael — then he's just a very stubborn, irritable and insecure boy. But when the stress proves to be too much for him and things are not going the way he wants them it tends to NOT end up very well.
  • Mama is usually a kind and carefree house lady that is until the stress of housework starts to wear her off and she decides she wants to chill herself out with some broom-flying. Or when she comes across something round — just RUN!
  • Miruru looks like a cute, harmless cat-girl and acts like a total ditz most of the time but at least in the first season she was one of bad guys' henchmen and did some pretty nasty things. She GOT Better but her selfish attitude didn't really changed.
  • Muse is totally moe and looks like she's always on the verge of crying, but being one of Silky's henchmen means she's also actively plotting how to prevent Noelle from becoming an angel - although it's true that she did most of it for Eros.
  • Sara when dieting like crazy.
  • And also Ruka beating poor Eros to death in Episode 19.
• Inuyasha:
  • The Soul Piper is a kind youkai who entertains the souls of deceased children until they are ready to move on to the afterlife. However if one of its charges misbehaves its eyes will begin to open. Once fully open, the Piper wraps the culprit in chains, returns them to their place of death, and drags them into hell. Even then it may still relent if the child has a change of heart.
  • Jinenji is a friendly and warm-hearted half-demon who lives peacefully in his field. But when a man-eating demon attacks him, he shows that he is also very strong.
  • The sequel series Yashahime: Princess Half-Demon shows Towa Higurashi. Of the three Yashahimes, she is probably the most powerful, but she is also the kindest and warm-hearted (perhaps because she was raised in the Morderne). While she's almost always cheerful and serene, she goes berserk when she meets Homura and finds out that he was the one who started the forest fire that nearly killed her and her sister.
• Touko Sakurajima, one of the two protagonists of My Girlfriend Cheated on Me With a Senior, So I’m Cheating on Her With His Girlfriend, is a kind and generous woman... But when she learns her boyfriend is cheating on her she becomes determined first to confirm it and then to make him regret being born by making sure he becomes completely dependant on her and then publicily expose his cheating and dump him on Christmas Eve - and to have the other protagonist do the same with his cheating girlfriend. As for the other protagonist, Yuu Isshiki, he's known as a very nice guy... But not only he goes with Touko's plan, his best friend later reminds him he has a history of violence when furious and he's glad he didn't just attack the cheaters.
• JoJo's Bizarre Adventure:
  • Jonathan Joestar, the first "Jojo", is a kind and mild-mannered gentleman. Nonetheless, he is not above fighting when his friends and family are in danger, not to mention the time he flew into a blind rage when he realized Dio Brando ruined his budding relationship with Erina and gave him a No-Holds-Barred Beatdown.
  • His great-grandson, Josuke, is a cool-headed and friendly individual in spite of his appearance, and will not, under any circumstances, kill anyone. Threaten his mother, hurt his friends, or make fun of his hair, though, and you'll wish killing you was his aim.
  • Kakyoin from Part 3 is arguably the nicest of the main characters, being polite and respectful to friends, allies, and bystanders. However, he's equally merciless towards enemies, deeming them beyond redemption, leading to him straight up murdering them if given the chance. Just ask Gray Fly/Tower of Gray. He will even resort to belittling his opponents, especially if they underestimated him. He once stooped to feeding an Enfant Terrible enemy their own feces as punishment for turning his friends against him and trying to kill the group in their sleep with its dream-manipulating power that had the ability to make its victims forget everything that happened in the dream upon awakening.
• Shun Uruma from Juujika no Rokunin. He’s only 12 year and ruthlessly tormented by five of his classmates just for the sheer heck of it, but he puts up with it thinking they will eventually grow bored and leave him alone, while worried that he would only trouble his parents if he admitted all of his bullies’ cruel deeds. Eventually he can take no more of it and tells his parents of what’s happening, but refuses the name-check any of his bullies. So he transfers to a new school and his family even moves to a new home. The bullies didn’t take this well and their leader kills his parents and beat his little brother into a coma, all because they were in the middle of their experiment to see how much torture Uruma could take until he’s Driven to Suicide. That was the last straw for Uruma, so he moves in with his WWII veteran grandfather, who trains him in the ways he was back in the war, and enacts his bloody, gruesome vengeance against all that have wronged him.
• Nagisa Kashiwagi from Kaguya-sama: Love Is War. Resident Nice Girl. Founder and president of the Volunteering Club. Member of "The Shuuichin VIPs who do heartless actions without giving them a second thought".
• Nanami of Katanagatari gives us the impression of just being Shichika's demure, Delicate and Sickly older sister. Then comes Episode 4 and the Maniwa Insect Squad with the intent of capturing or killing her, and it turns into a one-sided slaughter. She even gives off a Slasher Smile while she's at it. It's also worth mentioning that at this point of the story she seems to be the strongest character in the series, who's not only immune to non-lethal poisons and generally unable to die, but also able to learn most techniques by seeing them once and master them after seeing or using them a second time (not to mention that she's probably ridiculously strong, since she was able to easily fight with the main character knowing same techniques as him). You should never underestimate nice characters...
• Miu in Kenichi: The Mightiest Disciple. Normally she's very amiable and rather pacific, but if you put all her friends on the verge of death? She snaps and can no longer recognize friend from foe and will kill anyone who gets in her way. Not that she actually managed to before Kenichi stopped her. Miu mentions offhandedly that one of the reasons her grandfather travelled with her as a child was probably to get her immense rage under control. Possibly runs in the family, judging by her father.
• Kaze no Shōjo Emily: Emily is usually a Blithe Spirit, but when Rhoda bullies her and Ilse fights with her, Emily doesn't take it lying down and fights back with everything she's got. By the end of her and Ilse's fight, they're both covered in dirt and roughed up, and Emily convinces Aunt Elizabeth that they were dragged by horses when coming home from school to escape punishment.
• Kimba from Kimba the White Lion is a sweet and caring lion cub who is willing to help out those in need, a diplomatical and peaceful leader who tries to avoid fighting, and is more than happy to forgive those who want to reform themselves... But he also has super strength and vitality, the ability to summon many powerful creatures, which ranges from boulder-carrying hawks, and powerful chimps that fight along side him, and he puts all of that to good use in the battlefield; just look at all of the hunters, rhinos, hyenas, and other big cats he defeated.
• Kill la Kill: Mako Mankanshoku is The Ditz, a Cloudcuckoolander of the highest order, the show's resident Butt-Monkey, and generally the sweetest, most openly affectionate character in the show. She's also someone who will face death with no fear in order to protect her loved ones. Not to mention that, when she actually recieves the setting's powerup macguffin, she's among the strongest combatants around.
• Yuuri Shibuya from Kyo Kara Maoh! is a 15-year-old high school student who is dragged into an alternate fantasy world and made the king of demons. He is fairly average, kind, considerate, even tempered, and doesn't really stand firm. However, he has the ability to use extremely powerful magic that is activated when he becomes extremely emotional. When he does reach this point hes suddenly an extremely stern and violent alternate ego that can control water and other materials to his bidding.
• Umi Sonoda from Love Live! is arguably one of the nicest and competent members of µ's and one of Honoka and Kotori's closest friends, which means that doing anything to piss her off, such as abandoning your dreams of being a school idol, will not end well for anyone who dares do so. Honoka found this out the hard way in Episode 11 of Season 1 courtesy of a slap.
  Umi: (with a look of sheer contempt and betrayal) I never thought you were that kind of person!
• Of the two women central to the Leijiverse, Emeraldas is a merciless pirate and her sister Maetel is generally described as the Nice One: gentle, kind, a bit mysterious. The latter also blew up a planet because a mad doctor tried to steal her body.
• One episode of the Little Lulu anime involved Lulu wanting to join Tubby's club, a boys-only club, and Tubby's club agrees to let her be part of the club if she keeps the clubhouse safe. The first few screams come out as false alarms, due to her doing things such as accidentally falling off a tree and being scared by a bug. When she finally succeeds in scaring off the Westside Gang, after all of that, she is still denied entry into the club due to it being for boys only. Come next day and Tubby and his friends find the clubhouse completely destroyed. Lulu tells them she destroyed it and the flashback that follows reveals that the previous day she screamed in a fit of rage after being denied, and then mercilessly tore the entire clubhouse to pieces. Even Tubby is stunned by this when the flashback ends.
• Lucky Star:
  • Minoru Shiraishi in the Lucky Channel segments earnestly tries his best as Akira Kogami's assistant in hosting the show, despite how Akira constantly belittles and berates him. After putting up with 19 straight episodes of abuse from Akira only to get sent out to hike up Mount Fuji for three weeks, lose his spot to Daisuke Ono, and get yelled at by Akira because the water he brought back was warm, he finally loses his cool and trashes the set. He's even drawn slightly differently after the event, changing from his permanent closed eyes to tiny, pissed off ones.
  • Ayano, who's normally a Nice Girl, also has one of the series' most angry Blue With Anger moments. Her best friend Misao claims that she's actually quite scary when she's mad despite her sweet demeanor.
• Lyrical Nanoha:
  • Nanoha herself, whose sweet and innocent persona distracts from the fact that she has the power of a Physical God. Her favorite method of making friends seems to be beating them to near death and asking questions while she does it. And heaven help you if she actually gets angry. The oft-cited example of her blasting Teana to unconsciousness during a training battle ("Shall I... cool your head a little?") doesn't even come close to receiving her real wrath, which involves being on the receiving end of a Wave-Motion Gun. From across a battleship, if she has to.
  • Magical Girl Lyrical Nanoha A's:
    • Hayate Yagami, who is the master of a dangerous book that her guardians want to complete, as well as a sweet and caring girl that wouldn't hurt anyone. You can see where this is going. It does take a massive gambit to both give her the power to do this and a reason to snap, but snap she does.
    • Similar to Bleach's Unohana, Shamal is typically kind, polite and soft-spoken, but when she gets angry, even Nanoha is scared of her. This could be because the first time Nanoha encountered Shamal, she managed to use teleportation magic to steal Nanoha's Linker Core from afar, rendering her unconscious. Let's put this in perspective. She literally reached into Nanoha from a mile away, and effectively ripped out the core of her magic. And the scary part is, when they do that, there doesn't seem to be any counter to it.
    • The original Reinforce comes across as pretty Extreme Doormat most of the time, softspoken and obedient. The sound stages reveal that she is willing to let Hayate grope her breasts, and is willing to try to reach out and show kindness to Vita in spite of the latter's temper and angry rejections of her attempts. Reinforce very nearly destroyed the Earth because someone decided to greatly upset Hayate.
  • Magical Girl Lyrical Nanoha StrikerS:
    • Caro Ru Lushe. A gentle, big eyed, shy little girl, a B Class mage specialising in buff spells - what could she possibly do? Piss her off enough by destroying her home so she actually taps into her summoning magic and run for your Super Robot, because whatever she summons would be more than appropriate to fight it. That said, your Super Robot needs to be LARGE to even stand a chance...
    • Subaru Nakajima is known as "Gaogaigar-tan" for the enormous number of shout outs in her combat style, and the fact that she's literally a cyborg who resembles a young girl but was built for all-out physical combat (not that her origins matter much in that setting). Her berserker moment brought upon by her older sister Ginga being beaten near death and kidnapped by the Numbers is SO SCARY IT'S AWESOME.
      "Give her back. Gin-nee... GIVE HER BACK!"
    • And the battle nuns of the Saint Church, who can go from caring nurse to hard-boiled soldier in a matter of seconds.
  • From Magical Girl Lyrical Nanoha ViVid, Sieglinde Jeremiah is a shy and awkward girl who likes friendly competition. She is also nine-time winner of the interdimensional combat tournament. And when she loses her patience...
    Sieglinde: It's troubling if I've led you to believe you could walk away with your body intact after facing a Jeremiah at full strength.
  • Magical Record Lyrical Nanoha Force: Thoma's shown himself to be dangerous, but not in control of the power of his Divider through most of the manga. But when an attack on the Huckebein airship results in a massive melee, the carnage and the threat of his friends getting caught in the crossfire pushes Thoma almost over the Despair Event Horizon. It results in him fully activating the Divider Zero, draining massive amounts of magic and life energy from everything around it, nearly scuttling the Huckbein airship, and causing emergency resuscitation for several of the people drained by the Zero Effect his Divider created upon activation. Perhaps even more terrifying are Thoma's lines just before this happens, showing just how far he's been pushed. "Why is everyone doing such terrible things...to me and the things important to me? Everything that hurts. Everything that gets in the way. Fear, conflict, everything, and everyone...should just disappear." And in the chapter after that, after getting loose, Thoma contacts the Huckebein's boss and tells him in no uncertain terms that if he doesn't let his two friends go, he'll fire the same attack again, directly at the bridge.
• Elenore Baker from Madlax. Go ahead and touch her mistress, Margaret...Just ask Maurice Lopez.
• Magic Knight Rayearth. Shidou Hikaru is a bubbly, animal-loving, always ready-to-help fourteen year old girl but don't hurt her precious Umi and Fuu or she might end up wiping the floor with you. Her anger gives her such strength that she manages to make a considerable magic upgrade almost immediately after receiving her powers just because someone injured Umi!
• Joked around with in Mahoraba because it has two such characters. The first is Tamami who has her eyes closed and generally acts nefarious to the protagonist and to others. The second is the protagonist's teacher, Shirogane-sensei, who throws bad students into "the Closet".
• Haruka Minami from Minami-ke is actually the scariest character in the entire franchise... in addition to being a Yamato Nadeshiko in development (and an Onee-sama). She acts as a mother towards her two younger sisters. Remember how scared you got when you messed up & your mother lost her temper?
• Mobile Suit Gundam SEED:
  • Kira Yamato is generally a polite, soft-spoken person who cries easily, and as All-Loving Hero, he's careful not to kill his enemies in combat, preferring to just disable their mobile suits, at least after he gets the Freedom. However, when the Big Bad needlessly kills his Fallen Princess ex-girlfriend Flay right in front of him (and right after they had just found each other, after much misfortune), Kira chucks his "No Killing" rule out the window, resulting in a spectacular fight sequence that culminates with him ramming a beam saber through the villain's cockpit and leaving him in front of his Kill Sat as it fires.
  • Miriallia Haw. As Gundam pilot Dearka Elsman finds out, Do Not make a snide remark to her when she's grieving and there is a sharp object nearby. You WILL regret it.
• Mobile Suit Gundam Wing: Quatre Raberba Winner is The Smart Guy of the team, who is sweet, sensitive, and polite. But once he loses his father and one of this sisters and the people in his colony turns against him, he builds a Super Prototype Humongous Mecha with two Big Effing Wave Motion Guns and goes into a Tranquil Fury, destroying an entire space colony. Until he almost kills his best friend.
  • Building the Wing Zero was indeed the result of his going off the deep end and wanting to bring in an ultimate weapon to end the war. The resultant rampage (including the destruction of the colony), however, came about because he failed to realize why the design had been scrapped: the information overload of the cockpit caused a side effect of massive Mind Rape.
• Mob Psycho 100:
  • Mob himself is something of a strange and awkward fellow, but he is earnest, helpful, and humble. Which is why it is pants-ruining-ly terrifying when he reaches any of his various 100% emotional levels. God help you if you hurt anyone he cares about.
  • Relatedly, there's the bunch of Lovable Jock fitness freaks in the Body Improvement Club. Wholesome and unquestionably supportive, in direct opposition to the Jerk Jock trope, these guys support and encourage Mob and each other wholeheartedly, renouncing petty violence when asked by one of their school delinquents to help in a fight ... and the moment they hear that a rival school has kidnapped Mob, they instantly drop everything they're doing and kick ass to get him back.
• Wolfgang Grimmer from Monster is possibly one of the nicest people you will ever meet... But do not upset him. Really, don't.
• Monster Rancher: Golem is as gentle a giant as you could wish for and only really fights because he has no choice....but piss him off and it is massacre time.
  • Genki might count too, it never really happened in-show, but we are talking about an innocent-looking eleven-year old who regularly kicks genetically engineered dinosaurs, Living Weapons, and robotic stone dragons in the face and will headbutt anything. If he ever really lost it his general abilities, coupled with the ending to series two, suggest he would go absolutely Super Saiyan on everyone and thing in his way.
• My Bride is a Mermaid:
  • Sun Seto may be a Yamato Nadeshiko, but she is also a Mafia Princess and master swordswoman more than willing to fight in the defense of her loved ones. Case in point: after Maki, her tiny bodyguard and close friend, tried to publicly expose Akeno as a mermaid, Sun gave her a verbal scalding that left Maki genuinely terrified.
  • Her mother Ren is much the same; she's generally sweet and even-tempered, but is not one to be trifled with. She's also the one who keeps her husband Gozaburo in check.
• My Hero Academia:
  • The main character, Izuku Midoriya. He's friendly and awkward to the point of being downright adorable, and is a huge fanboy for all of the world's heroes. His dream is to simply be the best hero he can be and help others with a smile. He's also armed with the Quirk of the world's greatest hero, and he can and will kick your ass if you deserve it.
  • Appropriately enough, Izuku's mentor/inspiration All Might fits this as well. He's a classic All-Loving Hero with Hair of Gold, Heart of Gold who wishes to inspire the world and keep them safe with a smile on his face to comfort them. But when he stops smiling, you learn why angering the World's Strongest Man who is strong enough to change the weather with a punch is a bad idea.
  • Likewise, Ochaco Uraraka. A cute and charming girl whose main drive is to be a hero to support her family, and displays a cheerful disposition with everyone. But don't underestimate her sweet nature: when push comes to shove, she can push back with her gravity powers.
• My-HiME positively ADORES this trope:
  • Polite and graceful lesbian Shizuru Fujino had been nothing but kind and supportive to her best friend and object of her affections, Natsuki Kuga, for half of the show. Near the end, though, that same love made her evil, sending her on a rampage to eliminate anyone who came between her and Natsuki. Shizuru's fandom remained loyal, though irritated that the writers went a cliched route, and because it happened so close to the end of the series to have any real emotional impact. Consider for a moment that she gets so depressed that she kills herself in the Dating Sim based on the anime if the protagonist decides to wind up with Natsuki, and the previous event may not seem quite as ridiculous. Her popularity possibly gives her ending a note of hope, though, as well as a more sympathetic role in My-Otome.
  • Similarly, the normally bubbly and cheerful Shiho Munakata lets her jealousy overcome her sanity after some pushes from Manipulative Bastard Nagi, eventually leading to a showdown with the female lead Mai over a guy whom they both share as a Love Interest... leading to a no-win situation for poor Yuuichi. He ends up pulling a Heroic Sacrifice in the end to stop both Mai and Shiho from fighting..
  • Oh, and Reito Kanzaki? Mai's other love interest? The soft-spoken guy who wears all black? It turns out he's had the Big Bad living inside him for quite some time. One Post-Episode Trailer has Nagi lampshade this by saying something like "Come on...you mean to tell me he didn't seem suspicious from the start?"
  • Hell, Mai herself went into snap-out mode when she learned that Mikoto's actions led to Takumi's death, although it later turned out that Shiho was responsible. When you see her biting her lip and drawing blood, you know you screwed up big time.
  • In the manga, Takumi, Mai's Delicate and Sickly younger brother who's typically soft-spoken and considerate, turns out to be the Obsidian Lord.
• Takeo from My Love Story!! is a very strong example of a Gentle Giant, but the audience quickly learns he has his limits. When he rescues Yamato from a molester and the guy insists she was "asking for it", Takeo punches the guy's lights out.

N-R

• Naruto. The title character, who refused to give in to his emotions and extract vengeance upon the man who just killed both Jiraiya and Kakashi, levelled his village with the ground, and nearly killed Hinata, in order to break the chain of hatred has a malevolent, nine-tailed demon fox of immeasurable power sealed into himself—and this fox's power has a habit of seeping out of him whenever he loses his temper.
  • Also, Pain, the man who levelled the title character's village to the ground, who was unusually kind and sensible as a child, but made a complete 180 after he was given the ultimatum of killing his best friend Yahiko or seeing his other best friend Konan get killed, and Yahiko forced his hand and made him take the former option, all this after Nagato had made it his purpose in life to protect both of his friends, no matter what.
  • On the eve of the Uchiha Massacre, when those three Uchiha mooks confronted Itachi about Shisui's suspicious death and Itachi finally snapped, Itachi practically quoted this trope to them after he beat them all up in less than a second. Even afterward, Itachi still acted unfailingly polite in his screentime as an Akatsuki member. Though at this point most everyone already knew to beware him.
  • Chouji Akimichi and Hinata Hyuga, two of the nicest characters besides Naruto himself, also both qualify for this trope. Hinata's timid, Chouji's placid, and both characters are extremely gentle and kind. However, harm the people they care about, whether by mocking and taunting them (Jirobo and Shikamaru, in Chouji's case) or pinning them down and threatening to kill them (Naruto and Pain, in Hinata's case), and they will get angry. Very angry.
    • The databooks note the stark change in Chouji's personality by having two separate entries for him on the personality grid. Normal Chouji is more toward the calmer and patient ends of the spectrum, whereas "Pissed" Chouji is less so, and is one of the more passionate and less patient characters.
    • This trait of Hinata's gets expanded further in the canonical film The Last: Naruto the Movie.
  • Killer Bee is one of the nicest people in all of Naruto. The idea of holding a grudge is completely alien to him. He also beat Sasuke to within an inch of his life after the latter initiated an unprovoked attack on the former.
  • Hell, Naruto's kinda full of these. Might Guy loves his students with a passion, always has an encouraging word and will believe in them no matter what. He'll also support them with every skill in his arsenal. Everything—including opening forbidden seals that tear his body apart even as he tears you limb from limb. Then there's the Third Hokage, who alternates between a listening ear, guiding council and all round badass who was the strongest ninja of his generation, and then, to a lesser extent, there's Kakashi. Calm, collected, slightly goofy and pretty much an all-round-nice-guy... until you do something to piss him off, and then he shows you exactly why he's the Copy Ninja whilst he's smearing your face in the dirt.
  • A recent chapter has made, of all people, the God of Shinobi, Hashirama Senju, into this. His normal demeanor is, against all the legends and myths built up about him, very jovial, prone to outbursts of loud laughter, and not especially respected by even his younger brother. However, when the situation gets dire, his chakra aura becomes so powerful that just his glare starts destabilizing the foundation of a building, and everyone in a hostile environment is forced into a detente.
  • Then we have the epitome of this trope in the series, in the form of Himawari Uzumaki, who is hands down the most adorable, cheerful, and sweetest character in the series... but God help you if you ever make her mad; you wouldn't want her to take you down with a single finger poke that she literally just learned how to use, as her father Naruto and brother Boruto found out the hard way.
• When Nausicaa's father King Jhil dies in Nausicaä of the Valley of the Wind, the kind-hearted princess becomes a murderous embodiment of berserker rage who appears to revel in slaughtering the enemy (one man in the manga, an entire squad in anime) until Yupa stops her. Afterwards, though, she is devastated by the thought that her heart could contain such rage.
  • In the original manga, what sets her off is the Torumekians landing in the Valley without permission or quarantine (contaminating the Valley's crops and trees), having their knights attempt to pick a fight, defiling a grave Nausicaa dug, and bringing Worm-handlers into the Valley, whose slugs -- attracted by the scent of the trinket Nausicaa is hiding - slither up her body. The result of her snapping is the same, though.
    • For the record, Jhil dies of natural causes almost halfway into the story, long after Nausicaa leaves the Valley; she doesn't even find out until near the end.
• Negima! Magister Negi Magi:
  • Negi-sensei is a prime example. Normally the ten-year-old teacher is kindly to the point of adorable, but in later chapters he has been a particularly awesome example of this trope. At one point, he finds that three of his students have been enslaved, and one is being tortured by shock collars. Negi gives exactly one warning, and prepares to beat the guy to a pulp when he chooses not to listen. In addition, his acceptance of the power of darkness makes him so fearsome that even his students are uneasy.
  • There's also an incident where Satsuki freaks out a couple of guys who try to start a fight in her restaurant.
  • Another incident where a group of girls are playing Keep Away with Negi's ring/secondary wand in the bath. One of them grabs it and dashes across the water (it's a big bath) on magic shoes, leaping high into the air to get away. Tall, quiet Akira, who was helping Negi look for it, catches her in midair, hurls her into the water, then does the same to everyone else who was teasing him.
  • Also, do not get Chisame pissed at you. See that demon Negi in the link right above this? Rather than freaking out, she gets freaking angry at Negi for giving in to his dark side, while Nodoka and Kazumi struggle to keep him own she jumps in and slaps him upside the head. Keep in mind that Demon!Negi was in an Unstoppable Rage/Roaring Rampage of Revenge, tearing Kurt to pieces, and she stopped him dead in his tracks.
  • It has taken 280 chapters to get here, but we have finally found out what happens when you piss off Nodoka Miyazaki. Nobody actually gets hurt in the process, but the Big Bads' attack — until then verging on a Curb-Stomp Battle — was stopped in its tracks, and is now presumably on its way to a complete reversal. Good thing, too.
  • Chachamaru is a nice, soft spoken robo-maid, who has a crush on Negi. She can also call down a massive blast of energy which can obliterate an extremely powerful summoned demon by using the power of... cats.
• Neon Genesis Evangelion: Shinji Ikari is a loner and obviously has issues, but he's still generally quiet and meek. However, throughout the series, when the pressure on him proves to be too much, there's several occasions where he completely snaps and shows a violent, rage-filled side to his personality — most notably during his berserker attack on the Angel Shamshel.
  • This manic rage is mirrored in his Eva's attitude, since Eva-01 is notorious for destroying Angels in a berserk rage. Especially noteworthy is that the Eva contains his mother's soul, a woman who is portrayed as nice, sweet, motherly and calm when we see her in the flesh. She now inhabits Eva-01 and is stated to be the reason behind the Eva's fits of insane and unstoppable rage, given that they always happens when Shinji is in overwhelming danger. She takes it to the extreme when she reawakens Eva-01 without power and mutilates the then nigh-unstoppable Zeruel, eating the Angel alive and then popping off the binders controlling the Eva's true power.
• No. 6: Sion. Just check out his reaction when Rikiga suggests Nezumi become a prostitute or when he shoots a guy in Episode 10 for trying to kill Nezumi or in the novels when he nearly strangers a man for attempting to kill Nezumi. Nezumi even says Sion's not to be underestimated.
• One Piece:
  • The Straw Hat Pirates. In spite of them being one of the most notorious crews in the world, they're all kindhearted and easy to get along with, albeit quirky, and they never throw the first punch. But provoking them too much is comparable to digging your own grave; each member of the crew could effortlessly and singlehandedly take out an army, and they would declare war on the entire world for the sake of just one of their friends. And they did, and so far they've gotten away with it. While harming any of their friends, especially another member of the crew, will provoke a Roaring Rampage of Revenge, each member also has particular buttons that put them in full ass-kicking mode.
    • Luffy, the captain, is an Idiot Hero, but nice enough despite his foolishness. But don't harm any of your friends, don't insult his mentor Shanks, and do not damage his hat; out of all of the antagonists that have directly and seriously provoked Luffy, there are exactly two who haven't ended up at Death's door as a result, both of which are Big Bads in their own right. Rubber Man+Charles Atlas Superpower=Curb-Stomp Battle.
    • Usopp, the sniper, is a Lovable Coward and easily the weakest member of the crew, and he's typically glad of any excuse not to fight. But if you insult or mess with his captain, he'll show you exactly why he can keep up with the rest of the One-Man Armies in his crew.
    • Sanji, the chef, is a Chivalrous Pervert with more emphasis on Chivalrous (most of the time), and polite enough in all other aspects. But don't mention his wanted poster (which has a very crudely drawn image of him in place of a photograph), don't disrespect or harm women, and above all, don't waste food. He's on par with Zoro in regards to his Charles Atlas Superpower, and he can start Playing with Fire if the situation calls for it. Not to mention he actually uses his head and has been shown to take tactical detours to help his crew, making him the second most frequently used Spanner in the Works next to Luffy.
    • Chopper, the doctor, is a Ridiculously Cute Critter and perhaps the most childish and naïve member of the crew. But he takes his profession seriously; don't make a mockery of the sanctity of life, don't insult his deceased foster father Hiriluk or his foster mother and teacher Kureha, and don't abuse medicinal practices. His Multiform Balance doesn't lend him as much strength as Luffy, Zoro, or Sanji, but his strength is still monstrous, especially after the Time Skip when he gained control of his Hulking Out.
    • Robin, the archaeologist, is The Stoic of the crew, very rarely shaken by anything, always calm, composed, polite, and typically smiling. She's also a very skilled and ruthless assassin who had to live by her wits for 20 years before she found a home with the Straw Hats. If you don't want to end up having your body bent up and broken by her infinite arms, don't disrespect history or archeology, don't insult her homeland of Ohara or its scholars, and don't bring up the lies that the World Government spread about why she has a bounty on her head.
    • Franky, the shipwright, is a cool and compassionate pervert. He's also a very powerful cyborg, so if you have any good sense whatsoever, don't badmouth his deceased foster father/teacher Tom, don't harm the Thousand Sunny (the Straw Hats' ship, and his masterpiece as a shipwright), and don't take his speedo. Does that last one seem silly? It is.
    • Brook, the musician, is somewhere between a gentleman and a Dirty Old Man in his behavior. His preferred method of fighting can be summed up in four words: You Are Already Dead (mixed with Ghostly Chill after the Time Skip). Oh... but, he's already dead... Don't want to end up on the wrong end of his sword? Don't disrespect life, don't look at him like he's…leftovers, in a predatory context (for those not familiar, he's a reanimated skeleton), and above all else, do not damage his afro. Does that last one seem silly? It's not ^Explanation It's the only non-skeleton part of his body that he has left, and therefore the only way his old friend Laboon could recognize him.
    • Jimbei, the helmsman, is a noble fishman with a kind, gentle and jolly nature that befits his whale shark nature, and was considered a Father to His Men to his old crew, the Sun Pirates, and is practically like a third father to Luffy. He's also an Ex-Warlord who's mastered a fighting style that utilizes water to inflict heavy internal damage on his opponents. Don't disrespect the will of his late former captain Fisher Tiger or of the late queen Otohime of Fishman Island, don't discriminate against Fishmen, or promote racism in general, and especially don't assume he was an ex-slave because he's a Fishman.
  • Special mention should go to Conis, a sweet girl from Skypeia who was introduced as a Proper Lady-type character. After learning that her country's psychotic God-like ruler intended to destroy Sky Island and everyone on it and watching her father seemingly get killed by said ruler, she ends up driving a ship into the Sky Guards, facing down an angry mob that refuse to believe her, threatening the Sky Guards with a bazooka, and publicly shouting heresy to convince them that their god has abandoned them.
  • And, of course, we have Luffy's mentor, Red-Haired Shanks. Easily one of the most easygoing pirates in the world, he loves to party and is content to spend the whole day drinking away. He even shrugs off being physically abused, such as by having sake poured on his head. But like Luffy, he won't forgive anyone who hurts his friends. And he's not someone that you want to be a personal enemy of; he's one of the four strongest pirates in the world.
  • Whitebeard isn't quite as kindhearted as Shanks but is still A Father to His Men, and the islands that he claims as his territory are typically guaranteed peace and security as a result. Why? Because he is the strongest man in the world, and harming anyone who's under him will provoke a literally earthshaking Roaring Rampage of Revenge.
    • And in the Sabaody arc, we find out that it seems to run in the generations. Gol D. Roger—yes, him, the King of the Pirates himself — was quite easy-going himself in his youth. Then he learns His Days Are Numbered, so he decides on The Last Dance and sets out on a quest to traverse the Grand Line and find One Piece. He did it with time to spare, and it seems he did quite a bit of derring-do in the meantime. Oh, and one more thing from the Return to Sabaody arc: you know that nice hat Luffy got from Shanks? Shanks got it from his mentor: Roger.
• Gabu from One Stormy Night. He may be a sweet, kind, and caring wolf, but keep in mind that he is a wolf. When pushed past the breaking point, he will take an entire pack down.
• Mitsukuni "Honey" Haninozuka from Ouran High School Host Club is a short, blond cutie with a love of sweets and cute things, and is classified as the "lolishota type" member of the club. Renge cheerfully squeals about how he's so Moe. Harmless, right? WRONG! Honey just happens to be a black belt and heir to a family of VERY skilled martial artists. He's kicked the ass of grown soldiers twice his size, and strikes terror with a single look into the other hosts when they accidentally spill tea on his favorite stuffed rabbit.
  • Morinozuka "Mori" Takashi, Honey's cousin. He's usually very quiet, stoic, and passive... until he needs to kick ass. He's skilled in karate and judo, and is in fact a national champion at kendo. He and Honey make a formidable team.
• PandoraHearts:
  • There's Leo, who actually has a temper as bad as his master Elliot. He just doesn't lose his temper as often since Elliot loses his own faster and that lets Leo regain his composure. Still doesn't mean that it's a good idea to try to piss him off, though. Also, it's generally a bad idea to try to cut his hair without his permission, which doesn't seem to ever be given, anyway. Then, there's the fact that he's the current Glen Baskerville.
  • Oz himself counts as well on numerous occasions. In Volume 2, when he's with the Intention and she mentions getting rid of Alice, he shoots her emotionlessly and smiles. In Volume 3, he throws a huge fit at William West, who is killed by Vincent anyway. In Volume Five when he witnesses Alice's death, he goes absolutely INSANE and decides to destroy everything that makes Alice sad. He then goes on to say he'll destroy Alice, too. *In Volume 13 is probably where we see the normal, happy-go-lucky, carefree Oz at his scariest. Basically, the villain has hauled off his best friends to be murdered and intends to kill all the innocent people at a party and lied to his followers and believes religion is "just a way to brainwash" and decides to throw people down into the same hell he escaped from. Elliot (who is notable for having a tendency to flip out over the littlest of things) points out that he thought Oz sounded off even though he said he was okay. Oz says he'll never forgive Yura or his dumb rituals....he'll lay waste to it all himself. The background shows Oz, though tranquil, as incredibly angry, and Elliot is scared. Let me repeat: usually, Elliot is scaring the crap out of meek, mild-mannered Oz by yelling at him, but if suddenly he's scared, beware.
• Pokémon: The Series:
  • Ash's Pikachu. No, really◊.
  • There's a Dragonite in one of the later Johto episodes that goes BATSH*T CRAZY after the Team Rocket trio grabs the Idiot Ball again and decides to steal a relic that she was guarding, resulting in the Dragonite destroying a significant portion of the garden she lived in while in an Unstoppable Rage. This has a sad turn in the end, as after Dragonite snaps out of it and realizes what she's done, she breaks down crying. The worst part? Dragonite are normally FRIENDLY.
  • As of Best Wishes, Cilan. When he gets genuinely angry, he really gets angry. Though his flip-outs have been mostly played for laughs.
  • It's not limited to heroes: James of the Team Rocket trio has typically been characterized as more pleasant and cheerful than his teammates, and a borderline Extreme Doormat to boot. He's only had two real flip-outs — one of which involved him trying to steal a skyscraper because his bottle cap collection had been stolen. The other had him attack Jessie and Meowth when they refused to team up with Ash, even though there were baby Pokemon--including James' Mime Jr.--in danger. Both of these happened before Team Rocket Took a Level in Badass.
• In Pokémon Adventures, Yellow is everyone's friend. But if you threaten her forest in any way, you will be thoroughly stomped on by her usually-normal Pokémon roster... boosted to the mid level-80's on good old Viridian ragepower. Good luck, you'll need it!
• Sasame from Prétear is one of the kindest members of the Leafe Knights. He's always supportive towards Himeno, tries to be the voice of reason among the older knights and resolves fights...And he's secretly in love with the Dark Magical Girl. When he realizes that she can't turn from the dark side, he snaps, performs a Face–Heel Turn, and then tries to kill the other knights under her orders.
• In general, Pretty Cure does it with just about every one of its many Magical Girl Warriors. When you hear "This Is Unforgivable!", expect this trope to come out very soon.
  • Komachi in Yes! Pretty Cure 5 is easily the most passive member of the cast, and her power is just a shield. Near the end of the series, someone manages to really piss her off. Turns out that shield can be used as an offensive weapon after all—and she carves out an interesting new feature in the landscape.
  • This was supposed to be Alice's schtick in Doki Doki! PreCure in that she's a very nice person with a very short temper, however due to certain tropes coming into play, what could have been Bullying the Dragon turns into Poke the Poodle.
  • Haruka Haruno in Go! Princess Pretty Cure may be a nice girl because she'll do anything what a real princess can do such as having friends and being polite to others. However, when she saw someone getting hurt, she'll not hesitate to transform and punch you in your perfect teeth.
  • Nodoka in Healin' Good♡Pretty Cure is a sweetheart who would gladly put others before herself. She spends one of the final battles kicking ass and telling the parasite that was the cause of her Delicate and Sickly status that she isn't a tool to be used out of convenience and she does deserve to put her well-being first.
• Gentle, selfless, fatherly Shuuichirou Oishi from The Prince of Tennis is pretty much the Team Mom of the Seigaku team. But press the very few buttons he has? Let's just say that pretty much no one can stop him in the two or three times he loses his patience on you. Well-shown when his beloved partner Eiji says something insensitive about him in public and Oishi screams and tosses Eiji to the ground.
  • And it's not only Oishi, either! Shuusuke Fuji also looks and acts cheerful, pleasant and polite, but if you do anything to piss him off (especially if you hurt/threaten his friends or his little brother Yuuta), you should pray he's not your next tennis opponent or isn't near to you for quite a while.
  • Outside of Seigaku, there's little Data Player Taichi Dan from Yamabuki. Sweet, feminine-looking, naïve, etc - and is capable of yelling at Jin Akutsu, one of the most violent players in the whole circuit. Dan can be said to be Akutsu's Kid with the Leash, in a sense.
  • Not to mention Seiichi Yukimura of Rikkaidai. He looks feminine and kind, is very polite and soft-spoken, and strongly reminds you of the perfect Japanese woman... but he turns into a Knight Templar once he's on the court, by making his opponents lose their hope of winning. Need I say more?
  • Saki, one of Kozue's alternate personalities, could arguably apply, though she wouldn't necessarily become a threat to health and sanity. Her Break the Cutie threshold is insanely low.
• Psychic Squad:
  • Shiho from gets more and more aggressive tendencies as the series progresses — sometimes to sadistic levels. You really don't want her to use her telepathic abilities on you when she is in one of those moods.
  • Episode 40 confirms that this applies to Minamoto as well. Piss him off and you risk getting a bottle smashed against your skull or having him remotely operate a giant drill vehicle and demolish the premises.
• Raideen: Mari is a kind-hearted girl, but is also easily set off by people provoking her. Akira thought it was a good idea to prank her and got beaten as a result, while Dan also got clobbered for staring up her skirt. Poor Rei also endured an earful from her when she mistook her for flirting with Akira (though this is more of Mari being a Clingy Jealous Girl more than anything).
• Ranma ½:
  • Explicitly parodied: when the family is convinced the normally serene and placid Kasumi has finally snapped after they thoughtlessly went out to dinner without her and return to find evidence of a major psychotic tantrum. They're on the verge of "sacrificing" Ranma to appease her anger when it turns out the damage was all from Kasumi's attempts to capture a cat that had gotten into the house.
  • Used straight in the "Evil Ogre" manga arc and "Faster, Kasumi! Kill, kill!" OAV: When Kasumi is possessed by a vengeful ogre that makes its host act on their "most evil desires" everyone is terrified by the possibilities as she sweetly goes about adding little evil twists to her normal daily routines. Fortunately Kasumi's most evil desires don't extend much beyond spreading tacks in her father's bedding, embroidering "Okama" ("queer") on the back of Ranma's shirt, ordering tons of expensive takeout food inappropriately early in the morning and cutting cloth dolls out of the sheets.
  • Ranma's mother Nodoka Saotome is a rather nasty swing on this trope. She's a kindly, sweet woman whom both Ranma and Akane look up to, with the latter being implied to consider her almost a substitute mother... however, she is even more prone to put Honour Before Reason than any of the other cast members. Even though the Seppuku pledge her husband made is so vague that nobody else would even consider it to be worth the paper it was scrawled on, she's so devoted to it that she carries a sword everywhere she goes, just in case she meets Ranma and she decides he's unmanly. And that means everywhere- she's even shown sleeping and bathing with it. And it doesn't exactly take much for her to start pulling it out, either.Fortunately, "turning into a girl" doesn't count as "unmanly".
  • Ranma himself, despite being a jerk can fall into this category. Under normal circumstances, Ranma is a rather cynical, reserved un-socialized jerk, but despite his tendency to insult people, usually by accident and being unaware of normal social mores, will go out of his way to even help people that have in the past tried to kill, humiliate and/or rape him/her. If you want to know the result of getting Ranma actually angry, all you have to do is ask Saffron what made him re-incarnate most recently. Heck, his opening move in that fight was to slice off Saffron's arm, whereas up to this point he was one of the few characters tended to go out of their way not to use maiming or lethal force. Do NOT endanger Akane.
• Yamamoto Takeshi from Reborn! (2004). Put a baseball in his hands, or tell him to throw or hit something, expect him to get a serious samurai look and go absolutely all out on a simple game or task. Ask a poor, injured Lambo who just wanted to play catch. Though... this comes in handy sometimes.
  • Tsuna, especially when Genkishi decided to say he left Tsuna's friends for dead. Here comes the berserker rage.
  • Poor Yamamoto, the usual happy man, was nearly chopped into two, possibly paralyzing him. And Tsuna, who was planning to step down from the position of Vongola Boss, doesn't do that, but willingly accepts it, with a pained look in his eyes as Yamamoto's attackers the Simon Family, were right beside him. Whether that new family has gone past Moral Event Horizon, to hurt the Vongola, specifically, Yamamoto, Tsuna's still very... very upset. It's not normal for Tsuna to lash out, though, obviously.
• In R.O.D the TV it is eventually revealed that this happened with Yomiko and the Library. Joker kept pushing her and, when he finally revealed what he'd done to her lover... let's just say there's a reason you don't antagonist a Papermaster inside a library, especially THE Library.
  • Sena is generally a Nice Guy with being a bit of a coward. But insulting his teammates is one way to tick him off and you'll pay a heavy price.
• Roll Over and Die: Flum is usually a sweet and sensitive woman, eager to please, but push her hard enough, and she won't hesitate to chop you to pieces if she has the chance.
• Rosario + Vampire:
  • San Otonashi, a sweet, little girl (okay, not really that little) who doesn't speak and hates confrontations. She's not incapable of speech; her muteness is a conscious decision. Her monster identity is a siren, so her voice kills people. A villainous siren learned this hard way, as she gave off the impression of only singing a defensive song to protect her friends, when in fact she'd been singing another song at a pitch too high to be heard that was tearing him apart from within. Later, in the final arc of the series she is fighting on par with two of the Dark Lords, the strongest monsters who once defeated the Big Bad and sealed him years before.
  • On the same note, after Tsukune gets his 'upgrades', it's generally not a good idea to bait him by attacking his friends. And now he got those 'upgrades' under complete control, hoooo boy....
  • Outer Moka is herself no slouch; in the second chapter of the series, she defenestrates Kurumu upon learning from her other self how much of a bad idea leaving Tsukune alone with a succubus really is. It's not as bad as it sounds only because Kurumu can fly, but it makes one wonder if Moka knew that at the time...
• Rurouni Kenshin has Kenshin Himura. The guy is a soft-spoken Martial Pacifist whom his girlfriend occasionally hits, and always tries to talk first and only attack later. But do not piss him off enough to have the Battousai, his Superpowered Evil Side of sorts, come out. We warned you.

S-Z

• Sailor Moon:
  • Hotaru Tomoe/Sailor Saturn is a nice, peaceful girl... who can beat the demons just by looking funny at them.
  • Ami Mizuno/Sailor Mercury might be a shy little Cute Bookworm, but on two separate occasions, one being an incident where the monsters attacked a daycare, and the other where a monster who Ami thought was a rival in academics, she managed to unleash hell on either enemy.
  • Despite her being a Huge School Girl, Makoto Kino/Sailor Jupiter is a Nice Girl who cares immensely about her friends, old and new even going as far as to donate blood to an injured old friend. Do NOT attack Usagi, lest you be on the wrong end of a Curb-Stomp Battle, even with her being anemic from the blood loss.
  • Minako Aino/Sailor Venus is a loving girl who can't help but help people even to her own detriment, and is a blood donor. She also has lost any and all qualms about using deadly force against the enemy, as shown in the manga when she killed her true love because he was on the Dark Kingdom's side, and when Makoto got Brainwashed and Crazy and attacked Usagi she brutally dispatched her with a single kick.
  • Usagi Tsukino/Sailor Moon is the nicest one of all. When she discovered that one of Minako's friends from London was the reason of Minako's (then) latest heartbreak, she didn't want to cure her from being turned into a youma but straight-out kill her until Minako convinced her otherwise.
• Andromeda Shun of Saint Seiya is a Technical Pacifist and is, on more than on occasion, called the kindest and gentlest of the five main Saints. He's the kind of guy who begs his enemies not to fight and lets them beat him within an inch of his life rather than fight a battle he doesn't believe in. That is, until you try to kill one of his friends. And lord help you if you're the bastard who murdered his teacher...
  • This trope is also the hallmark of the various incarnations of Hades, God of Death, mortal rival to Athena, and the instigator of the various Holy Wars throughout history. Andromeda Shun is the newest incarnation of Hades in Saint Seiya. Meanwhile, in the prequel series Saint Seiya: The Lost Canvas, a meek to a fault young boy named Alone is Hades' next vessel. He is the best friend of the current Pegasus Saint, Tenma, as well as the current incarnation of Athena, Sasha. His first act upon his transformation to Hades is to burn down their home town and massacre everyone in it.
• Cho Hakkai in Saiyuki is polite and quiet-spoken and generally the nicest of the protagonists... unless he's pushed too far. When he really lets loose, he terrifies even makes-the-gods-nervous Goku. Sanzo has no qualms about taking on Goku or Gojyo in a tournament side chapter, but is nervous at the idea of facing Hakkai without his sutra.
• Stepford Smiler Kafuka Fuura from Sayonara, Zetsubou-Sensei hides a bloodlust that makes those who are acutely aware of her cheerful facade mortally terrified of her. Her classmate Meru takes one look in Kafuka's eyes and is confident that one day, she will kill them all.
• School Days: Makoto Itou really had it coming.
• Sgt. Frog: Fuyuki is normally an Extreme Doormat. Push him far enough, though, and everyone including Natsumi becomes scared of him.
  • Dororo is perfectly content to lounge around all day, drinking tea, and enjoying nature. But when the chips are down, he isn't afraid to demonstrate the skills that made him a top assassain back home.
• Shadow Star loves this trope, but the best example by far would have to be the local Lonely Rich Kid, Hiroko "Hiro-chan" Kaizuka. She's a quiet Ojou in sixth grade who is mercilessly bullied at school over her excellent grades, while at home her parents berate her whenever she gets anything less than a perfect score on any test (even though she's pressured by the bullies to do badly lest they torture her more). She tries enduring this abuse as best she can while remaining unconfrontational, but when the bullies take their actions to monstrous degrees and her father tries cutting off her ties with her only friend... well, let's just say she puts her new shadow dragon to very good use. The results are messy, to say the least.
• Jeanne, leader of the X-Laws in Shaman King, is a small 11 year-old girl gifted with Incorruptible Pure Pureness and huge amounts of charisma, who manages to win over almost everyone who meets her (at least initially) with her selflessness and grandiose speeches about justice and peace, and she's also on a mission to kill Big Bad Hao Asakura. She's also a Knight Templar supreme (in charge of an entire organization of Knight Templars) who messily executes her opponents with giant torture devices (and even spends most of her time locked in an iron maiden, and her Over Soul has her attached to various torture devices as well.) There are no Enemy Mine agreements to be had with her, either. Either you're an X-Law, or you're the enemy, and will probably meet the same bloody fate as Hao's forces if you have to go up against her.
• SHUFFLE!:
  • In a flashback, we see Kaede Fuyou go off the deep end on the male lead after her mother's death (Boxcutter Kaede), an effect that is repeated near the end of the series when the lead starts seriously going out with another girl. Kaede and the lead, Rin, have effectively been living as husband and wife for close to ten years, which can be seen as Kaede trying to repair the damage her other self caused to Rin.
  • Then there's Nerine, seemingly one of the sweetest girls in Rin's harem; until she hears you bad-mouth Rin. Then, well, as she would say, "you need not fear prolonged suffering in the hospital"; Her dad, Satan for all general purposes, is actually proud that she only blew up the gym.
• Nadeshiko Fujisaki of Shugo Chara! sweet, calm, polite, and all around pleasant...that is, unless, you happen to spark his character change.
• Soul Eater:
  • Tsubaki is usually shy and humble. Thus, when she finally and truly stands up for herself in the fight against her brother, the result was pure awesome.
  • Similarly, this series' personification of Death is not only a good guy, he's funny-looking and goofy — but that's just a form he uses to avoid scaring his students. Pity the villain who's dangerous enough to make Shinigami-sama go old-school. The last guy who did that had his skin ripped off in one pull and then he was forcibly cocooned inside it. *shudder*
  • Same goes for Demon Hammer Marie Mjolnir, a lovely, sweet lady who is also known as the 'Crushing Weapon' for a reason. When confronting the murderer of BJ, Justin Law, she reacts to the possibility of him harming her students by landing a punch on his chest so hard he's thrown into the air. This comes after Justin, having clearly forgotten what series he's in, points out that though he and Marie are both Death Scythes, she has only a "woman's power"..
  • Spirit shows hints of this when he loses his temper with Medusa.
  • Patty's The Ditz, but she's a better fighter than she looks. She grew up on the streets, surviving by helping her older sister Liz mug random people. When she gets serious, she is much more horrifying than her Deadpan Snarker sister.
• In Sound of the Sky, Filicia is the soft-spoken, glasses-wearing Team Mom. Well, as long as you don't threaten or abuse any of her squad members, which'll make her remind you that she is after all a Lieutenant of the Helvetian Army and a survivor of the battle of Binnenland.
• Wako Agemaki of Star Driver, the ever peppy south maiden, had never had a true moment of rage during the show. Then came Episode 19. When Glittering Crux member Kou takes over Takuto's body, and tries kissing her. Something Takuto would never do. Did we mention it was her birthday? She puts Sugata's knife to her throat, complete with Death Glare, and drawing a little blood, and tells her, in no uncertain terms, it doesn't matter if she's controlling his body. She will cut her.
• Stepping on Roses has several characters that start out as kind and caring, but through the series' events become deceitful, manipulative, or even all-out crazy... The most notable example of the latter is Nozomu. On the other hand, Nozomu's arranged fiancée Miu turns out to be very scary after being subjected to some dashes of the Break the Cutie...
• Eto Kai from Switch (2002) is typically very gentle and kind, however, if you even think about harming Hal, you'll find him significantly less agreeable.
• Sword Art Online:
  • Kirito, the main protagonist, is as nice as you can expect from a teenager who enjoys playing MMORPGs, and will not hesitate to help anyone in need. Say your prayers if you ever incur in his rage by harming innocents, his friends or family. In the climax of Alicization, PoH decided to keep taunting Kirito even after Kirito had just mopped the floor with him, so Kirito subjected him to a Fate Worse than Death, to give you an example.
  • Asuna, Kirito's girlfriend, is no slouch either, she's a very sweet and kind girl once you get to know her. Make her angry and she'll cut you down before you even see it coming.
• Symphogear: Hibiki Tachibana is someone who would rather befriend an enemy rather than fight them... But if she feels that they've gone too far, her fist will likely be the last thing they see.
• A recurring theme in the Tenchi Muyo! universe. The main characters of the series set in this verse are all unassuming Nice Guys. In the main continuity, their household is explicitly stated to be the single greatest concentration of Power in the entire universe. Make them angry and they will end you.
• Tengen Toppa Gurren Lagann:
  • Our hero, Simon the Digger, is a normally polite and gentle person who wants to follow his Big Brother Mentor on their quest to save humanity... then said Bro dies, and Simon goes completely Ax-Crazy. After he calms down, he forgoes anger and replaces it with determination and resolve, though he won't hesitate to fill someone's mecha with drill holes if they mess with anyone on his team.
  • For the bulk of the series, Nia is just about the nicest, politest, most innocent character in the entire show. Until you find out she's actually an Emissary of the Anti-Spirals, in charge of the extermination of Mankind.
• In That Time I Got Reincarnated as a Slime, Rimuru is a pretty happy go lucky guy who is content to just do his own thing and build up the prosperity of his people. He is self-effacing, reluctant to fight and generally forgiving of his enemies. Murder some of his citizens, including his personal secretary, and Rimuru has no compunctions about single-handedly slaughtering your entire invasion force down to the last man.
• Tokyo Ghoul has several of these characters, lurking in plain sight.
  • Protagonist Ken Kaneki is soft-spoken and clings to his mother's ideal of getting hurt rather than hurting others. However, he's also one of the legendary One-Eyed Ghouls and rapidly becomes one of the most powerful Ghouls in the series once provoked into abandoning his mother's creed. What follows is a six-month Roaring Rampage of Revenge, as he obsessively trains in martial arts and engages in cannibalism to increase his power as quickly as possible. The result is a mentally-unstable, incredibly powerful Ghoul that will do anything to protect the people he loves and believes in Paying Evil Unto Evil.
  • Yoshimura is a grandfatherly figure to the other Ghouls at Anteiku, and encourages coexistence with humanity. However, he is one of the most powerful Ghouls in the series and a Retired Badass that provides a Mook Horror Show whenever he comes out of retirement.
• In Tokyo Shinobi Squad, the Narumi-kai are famous in Japan for refusing to bow to money or influence and only taking honorable jobs that help people in dire straits. This kindness does not make them less dangerous than any other and they strike with lethal force when attacked.
• Toward the Terra has the Mu. They are a peaceful race of humans with psychic powers, who are hunted down like animals and chased across the galaxy due to Fantastic Racism and Deus est Machina. Seeing their new home destroyed along with their fellow Mu, whose telepathic scream they can hear, makes the survivors declare war on humankind and turns their leader into The Unfettered. They successfully conquer one world after another, leaving planetary defenses completely shattered, until humans finally mobilize all military forces and invent anti-Mu weaponry.
• Trigun's Vash the Stampede is the sweetest, most gentle, peace-loving guy you could ever wish to meet, and manages to stay so despite all the horrible things that keep happening to him, and acts like a complete goofball most of the time when he's not angsting. He regularly manages to defuse dangerous situations and deal with opponents with minimal force, and sometimes without even having to fire his gun, despite the fact that if he really felt like it, he could easily unleash holy hell on everyone around him and pretty much nothing would be able to stop him. But if you do what Monev the Gale did, like blow up an entire city block and kill dozens of people in an attempt to kill him... well, the good news is, he won't kill you, but the bad news is, you're still utterly screwed. The scene when he looms up out of the darkness with an expression of pure rage on his face and his eyes glowing solid blue is chilling. He then goes on to completely thrash Monev using a vault door, the last three bullets in his revolver, a shot from the literal Hand Cannon in his cybernetic left arm, and a solid boot to the face, and reduce the huge, previously unstoppable assassin to a blubbering mess on the ground, begging for his life (and Vash was damn well considering putting a bullet between his eyes too).
  • Notably, Vash did shoot to kill after Monev blew up the block. Viewers here a single gunshot and suddenly there's three bullets in Monev's helmet. The only reason he lived was that apparently his visor was bulletproof.
• The title character of TSUYOSHI - The One Nobody Can Win Against is a kind and somewhat naive twenty-something who doesn't like fighting. So, when someone is stupid enough to try and fight him he beats them up so badly they'll be too scared to try and get a rematch, with the beating usually including at least one Groin Attack. And when someone actually angers him, he'll put the fool in the hospital.
• Oyuki from Urusei Yatsura is kind and gentle in the extreme, if rather stingy. Once, Ran thought she had pissed Oyuki off and was so scared she ran, throwing live bombs and grenades after Oyuki just to buy time to escape. Oyuki seemed completely unbothered and the friends made up... however, Oyuki did give a stern (but softly spoken) lecture to the king lemming who had trashed Ran's place in the meantime, and the lemming ran off. Oyuki said, "Oh? Do you think you can run away?" The resulting punishment and collateral damage thereof caused no small amount of mental trauma to the lemming and any witnesses.
• Violet from Violet Evergarden may qualify as she is one of the most polite people in the story. However, she is not called "The Soldier Maiden of Leidenshaftlich" for nothing as shown in this scene when some soldiers get between her and her client.
• Keima's mother Mari, from The World God Only Knows, is a nice, simple Japanese housewife. Then Elsee pretends to be her husband's illegitimate daughter, and we find out she used to run with biker gangs...
• Yakitate!! Japan: Kirisaki Yuichi. Only in Episode 1 though. The rest, he acts as Pantasia's Main Branch antagonist and wishes to crush the "cockroaches" (that is Azuma's gang of the southern branch).
• Yu-Gi-Oh!:
  • Yami Yugi was never that patient with his opponents, but at least he tried to take a kinder route to defeating them, even if they threatened his friends. However, when he lost the soul of his partner, and local Jerkass Insector Haga tricked him into believing he had torn up the card that held it during their duel on a train during the DOMA arc...well, let's just say that it's a good thing that duels are supposed to end when a player's life points hit 0. To add a little irony, the card he used was called "Berserker's Soul"
  • The episode after that one when Yami Yugi "meets" Yugi's lost soul in a kind of cursed land—and Yugi forces him into a duel, all the while snapping accusations at the pharaoh, and throwing Yami's earlier, cruel tactics right back at him. It was a being cruel to be kind-type situation, but the fact that Yugi could be that harsh at all was a shock to many fans.
  • Anzu was livid when Seto Kaiba called Yugi weak for giving up after Yami Yugi nearly killed him in their duel, and she made herself clear. The fact that Kaiba threatened with suicide does not completely justify his criticism.
  • After spending most of the show taking a back seat to Yami, little Yugi ends up on his own in a duel against Bakura — and kicks his ass.
• Yuki Judai from Yu-Gi-Oh! GX. Completely lovable guy who gets along with everyone, including people who have tried to kill him: right up until five of his best friends end up dead (or so he thought at the time). Cue Unstoppable Rage on Brron and the advent of Judai's "if I have to be evil to stop evil, then I will be" philosophy.
  • And then he proceeds to conquer most of Dark World and suck up living souls to fuel Super Fusion with a loyal army of monsters at his beck and call. Brr.
• In Yu-Gi-Oh! 5Ds, Carly Nagisa is a sweet, eccentric girl whose love of The Lancer Jack Atlas is incredibly cute. However, when she gets tortured and then killed in a Psychic Duel trying to get information about the Arcadia Movement to help him, she turns into a Dark Signer and unleashes a certified, factory-sealed can of whoop-ass on her murderer, Divine, for robbing her of a chance to be happy with Jack. This is done in a fashion that would be horrific if the bastard didn't completely deserve it. Somehow, Divine survives the whole thing, but still. Dang.
• From Yuusen Shoujo - Plug In Girl:
  • Tsukihiko Fujiki is basically what happens if Shirou Emiya is learning Cyborg science instead of sword magic and a lot more cheerful. He's kind, considerate, and an all around Nice Guy. However, if he sees anyone in danger, he'll protect them. Considering most of his upper body is made of psychomaterial, he can copy any weapon he understands and he can be... creative when he utilizes it, all his fights tended to end in his favor. As long as he has enough stamina.
  • The first guy who defeated Tsukihiko, Yuuto Ryuuzouji, was a small, unasuming boy with a kind personality who hates confrontation, and doesn't like hurting innocents. Then it's Subverted with his Superpowered Evil Side, who is caustic, brutal, likes violence, basically everything his other personality isn't. Then Double Subverted with the "nice" Yuuto, who's actually a personality created for front for social situations. Because of his status as a created personality, he can have his body stuffed with psychomaterial up to 85%. And exactly because of this niceness, he doesn't hesitate to brutalize his enemies thoroughly if they happen to stand in the way of his objective, in order to end the fight quickly.
• YuYu Hakusho:
  • Kurama of YuYu Hakusho is generally polite to everybody else and arguably the nicest member of the cast... Unless you piss him off (threatening his mother is a good way to do that). Then he will kill your ass in very brutal and bloody way that involves lots of pretty flowers. Or worse.
    • Hiei noted this in an early arc, saying that Kurama's calm mind allows him to be as calculating and brutal as he wants without being distracted. He even says that, back when he was a Psycho for Hire Big Bad, he brought Kurama along as a partner to avoid gaining his ire in the future.
    • And in the Dark Tournament someone plays on his sympathy for an early lead and regresses his age back from his normal form all the way back to infancy and then to his previous incarnation as a powerful and ruthless Yoko. Bad move there, buddy.
    • And this is reinforced in the Chapter Black arc, where his opponent was a Creepy Child, and they were in a Deadly Game. He was forced to Shoot the Dog and was most upset about not being able to avoid killing the kid. Then he found out that his next rival was NOT who he seemed... It's a Fate Worse than Death for you.
  • Yukina is a kind, quiet and nice girl... And the one confirmed genocidal character in the show; she blames the other ice maidens for her mother's death, and is looking for her brother to remind him his oath to kill them all and bring him back home. In an ironic twist, it's Hiei who acts as her Morality Pet of sorts, pointing out that if she wants to cross the Moral Event Horizon she needs to do it herself (and she doesn't know he's her brother). Hiei actually had gotten back home long ago after Yukina had left to look for him, only to find they were Not Worth Killing.
• Zombie Land Saga:
  • Just because Sakura is nice and somewhat naive doesn't mean she's a complete doormat. In Episode 2, after getting fed up with Saki, Ai, and Junko's behavior during their performance, she doesn't hesitate to slap Tae's head out of Saki's hands and verbally rips into them in the form of a rap. In Episode 10, Sakura finally loses her patience with Kotaro's insane ideas and lashes out on him after her encounter with a wild boar in the snowy outdoors and then towards her group mates for seemingly goofing off. Then in Episodes 11 and 12, after she regains her pre-mortem memories at the expense of her post-mortem ones, her depression makes her so moody that she snaps at Lily and Tae for trying to help her when she just wants them to leave her be.
  • Yugiri is kind, beautiful, motherly, and has one hell of a hand slap. She's not above harshly scolding those who let their troubles get the best of them and will fervently try to get them to regain their senses. And come Revenge, she's revealed to be a skilled swordfighter and retired assassin.

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