This trope is a staple of shoujo manga, especially Magical Girl shows. So the heroine is Book Dumb, ultra naive, a Butt-Monkey or is just starting with her mission and/or training in magic? The Powers of Love and Friendship will ultimately give her strength to keep on going! The Ur-Example, obviously, is Usagi from Sailor Moon.
Belldandy from Ah! My Goddess. Behind that soft and caring exterior lies a will of iron and a girl who will stand up to the devil herself for the sake of those she loves.
In Asteroid in Love, Mira and Misa are polar opposites, but they share one thing in common: their insistence on self-reliance.
In the seventh chapter, Moe is going to tell Misa that Mira and Ao want to discover an asteroid together when Mira pulled Moe back, saying she'd rather do it by herself (i.e. without Misa's assistance).
Right after the previous scene, Mira gives Misa the banded stone she found during Chapter 4 as a good-luck charm for the latter's college entrance exams. While we immediately know Misa uses that for Mira's aforementioned Goal in Life, Chapter 31 revealed why Misa does that—she wants to do that herself.
In Attack on Titan, Sasha Blouse's energetic disposition and pluckiness lands her here. As emphasized in her introduction: Shadis sentenced her to run until she collapses, and she does it without complaint. What got her upset was being denied any dinner. Sasha later has several brushes with death, but never loses her optimistic nature.
Noelle Silva of Black Clover. She refuses to give up in tough situations, convincing Nozel that the elf-possessed humans do not have to be killed and will be saved by them. She passionately asks Patry to help her and the other Magic Knights grow stronger to defeat the Spade Kingdom. When asked what makes her think they can become strong enough in little time, she states that giving up is even harder than getting stronger.
After many, many ordeals and Break the Cutie episodes, both Rukia Kuchiki and Orihime Inoue end up graduating into this at different times.
In the Everything But The Rain arc, Masaki Kurosaki is this through and through. In a more quiet way, we may also count Kanae Katagiri.
Uryuu Ishida is also a very rare male version of this, being closer to this archetype than to the grim Determinator, and probably taking up cues from his Missing Mom aka the aforementioned Kanae Katagiri. It seems that his Face–Heel Turn has changed things, but then it' revealed that he's faking it.
Other plucky girls in this series are: Karin Kurosaki, Tatsuki Arisawa, Chizuru Honshou, Yoruichi Shihouin, Sui-Feng, Yachiru Kusachiji, Nanao Ise, Rangiku Matsumoto, Hiyori Sarugaki, Lisa Yadomaru, Mashiro Kuna, Tia Harribel and her Amazon Brigade (whose Villainous Valour was praised by Yamamoto before he nearly killed them), Senna from the first movie, Homura from the third movie, and recently Jackie Tristan and Riruka Dokugamine. As an Older and Wiser version, we have Kirio Hikifune.
Kita from Bocchi the Rock! is such an overwhelmingly optimistic extrovert that her "Kit-aura" blinds the more introverted Bocchi and turns the cynical Seika to ash.
All of the girls in Bokurano have their plucky moments, specially Anko Tokosumi, Kana Ushiro and Youko Machi.
Candace White "Candy" Andree from Candy♡Candy. She has her breakdowns, but as soon as she's back to her feet, she comes back stronger than ever.
Cardcaptor Sakura: Sakura Kinomoto to some extent. While she is rather determined and frequently shows little concern for her own well-being, her disposition better resembles that of a real child under such situations, as such she does actually show fear and break down at times, relying on her friends' support to recover her strength.
Case Closed has several: Ran Mouri, who either witnesses or is subjected to Break the Cutie many times but ultimately brings herself back; Sonoko Suzuki, who never loses her Genki Girl behavior for too long despite her amazingly bad luck; Masumi Sera, a Badass Bikerbifauxnen who does her best to help her friends and look for her missing older brother, Miwako Sato, who is a physically and mentally strong Action Girl; Hina Wada, an Action Girl who believes in aliens and says she'd love to "have a heartfelt conversation with them using her fist" if they tried to invade...
Charlotte (1977): No matter what, Charlotte is convinced she has to return to Canada and secure her farmland, going through hell and high water in working various odd jobs to keep it from drifting away from her name.
Kallen Kouzuki When faced against the now practically superhuman Suzaku, she fights him to a standstill, reducing both of their machines to scrap before finally destroying Suzaku's machine with the very last blow she has left before her machine shuts down. Suzaku even wonders aloud how he can't beat her, even with his "live" Geass.
Euphemia li Britannia and Shirley Fenette also count. Doesn't work as well, though.
Aura of Corsair boisterous, opinionated, and quick-tempered, and remains so even after she is kidnapped and threatened with execution.
Yumoto Hakone is a rare male example. He eagerly accepted his role as protector of the planet and he's usually the most proactive and energetic fighter during Monster of the Week battles.
Gora Hakone qualifies; it must be a family trait. His parents disappeared when he was young and he's had to raise his brother from infancy to adolescents by himself while running a business. Despite that, the brothers have a healthy relationship, the bathhouse provides stable income, and Gora remains mostly well-adjusted. That's not even counting his stint as a Magical Boy Warrior.
In Dear Brother and specially in the anime verion, Tomoko Arikura is a perpetually feisty Genki Girl who supports her shy and sweet best friend Nanako no matter what and always does so with a huge smile.
A Dog of Flanders (1975): Alois Cogez. Even after her father formally bans her from seeing Nello, she still visits on him on the day of the art contest and tells him she is praying for him. She frequently stands up to her father and insists on Nello's goodness, not caring if she gets punished.
Katsuhiro Otomo's early manga Domu: A Child's Dream gave us Etsuko, a little girl with immense Psychic Powers she uses to battle a Psychopathic ManchildSerial Killer. All the while she is spunky and headstrong, first responding to seeing him psychically manipulate a baby to fall off the roof of the apartment complex with, "What an awful brat you are! Really now?!" and scaring the old man by using her powers to rattle the bench he is sitting on.
Mai and Mami from Explorer Woman Ray, twin girls who travel to South America in search of hidden treasure, aiming to meet up with the Adventurer Archaeologist title character. Despite their youth, naivite and obvious inexperience, even being shot at by the bad guys in search of their stolen MacGuffin doesn't deter them.
Erza's an example of the more masculine Determinator trope.
Lucy is a more traditional example, as while she has cried in despair several times over the course of watching her friends and Celestial Spirits get hurt for her sake, losing her father and Never Got to Say Goodbye, losing her contract with Aquarius after breaking her key to save her friends, she still manages to pull herself together and remain cheery as ever.
Mavis Vermillion might be the pluckiest of all. For the record, her backstory is probably one of the most tragedy-filled of all the members of the members of Fairy Tail, and yet despite having been sent over the Despair Event Horizonafter being cursed into an Enemy to All Living Things she still managed to come back as bright and compassionate as ever.
Despite being helpless in combat and painfully knowing it, Sulia Gaudeamus keeps going on and doing her best to help Terry, Joe, Andy and Mai stop her evil brother, Laocorn, and save him from himself. And if she has to commit suicide to save him... she will.
Kim's wife, Myenungsuk. When Kim was in the receiving end of a Curb-Stomp Battle, she kept her cool and her trust in him, refusing to cry and break down for the sake of him and their kids as well as herself.
Tohru Honda from Fruits Basketplays with this trope. She still is optimistic despite being orphaned, temporarily homeless, and living in a tent, bullied in the past, and helping a whole Dysfunction Junction with their trauma. Then we learn that this is her way of dealing with all the pain in her life—she's not exactly a Stepford Smiler, as she is sincerely happy often, but she also uses it as a way to keep from succumbing to grief and accepting that her beloved mother is gone. And then... it's reconstructed and reinforced: when a maddened and despaired Akito tries to definitely break her as the members of the Dysfunction Junction are being released of their curses... Tohru acknowledges that not so strong part of herself, accepts it, and manages to kindly speak to Akito and offer her kindness as well. This finally breaks the vicious cycle that has trapped the Sohma clan, and even when Tohru is severely injured after falling off the cliff she's standing, it kickstarts Akito's Heel–Face Turn, and helps Tohru herself to deal with her own suffering.
Fuuka: Fuuka is an optimistic, energetic girl - and once she gets inspired, it would probably take a speeding truck to dislodge the idea from her head.
Hajime Ichinose from Gatchaman Crowds. She's actually so cheerful and strongwilled that she can get Berg Katze to back off her case, simply because they is no darkness in her heart.
Maya Kitajima and Ayumi Himekawa from Glass Mask. The first decides to fulfill her dream of being an actress despite how odds always go against her, the latter refuses to have things handed to her and wants be famous for her own merits.
Hanako from Goodbye, My Rose Garden may be an easily flustered bookworm, but she's notably strong-willed and determined, speaking out against any injustice she witnesses or experiences. In her Establishing Character Moment, when a book publisher brushes off her attempts to contact the writer Victor Franks, with his justification being that Franks would be uninterested in a woman's "emotional" writing, Hanako snaps and tells him that she didn't cross an ocean simply to be mocked. The noblewoman Alice Douglas witnesses this outburst, and later cites Hanako's unshakeable will as the very thing that made her decide to hire her.
Wendy Garret of GUN×SWORD has all the stubbornness of the Determinator combined with a sometimes inordinate amount of optimism. The introductory narrative to the second episode explicitly indicates that Wendy symbolizes hope in opposition to the despair of her partner, Van, but it wouldn't be hard to figure that out without the narration.
Ohana Matsumae, the main character of Hanasaku Iroha, is an interesting take on this Trope in that her pluckiness is presented as both a weakness and a strength. On one hand, her optimism and sincere desire to help people lets her accomplish some good things, but on the flipside her tendency to dive headfirst into something without a solid gameplan does backfire on her from time to time.
Hello! Sandybell: While in Scotland, Sandybell risked being hit and punished if it meant defying Kitty and saving animals. She also stood up to Charles' Gang of Bullies and refused to stop seeing Mark, in spite of what Leslie told her. She's also dedicated to getting news stories out regardless if everyone else at Ronwood's mocks her.
Most of the girls in Hetalia: Axis Powers. These're be comfirmed in their profile especially:
Belarus is described as one by Russia. But he quickly adds: "Inabad way."
Resident Lady of War Vietnam is one too, as her profile says she's "a very headstrong woman" and that "there are many strong women in her history".
Taiwan gets her profile in the fourth manga volume ("An island girl nation with a headstrong and easygoing personality!") She shows it via cheering up Vietnam, teasing her brothers, and interacting with all of them as an equal. "It's okay, us Taiwanese don't believe in bad fortunes!" It's confirmed by her Image Song, "Poipoipoi." 'Poi' means "poof," and it's used in-context as "making problems and bad luck go POOF!"
Korea, too. He will never ever give up chasing after his siblings, saying stuff "belongs to him" and being almost always unfailingly cheerful while doing so.
There's also Seychelles, who tries hard just to get people to know her name. She keeps doing it, and also manages to keep both England's arrogant behavior and France's lechery at bay.
Even Monaco, the resident Ojou has shades of this with sketches of her in armor and having her profile describe her as someone who worries a lot, but gives off a proud impression. She also has an attitude like this when it comes to poker.
Belgium, too. She sometimes frets over her Aloof Big Brother Netherlands, but most of the time she keeps her bright smile and her teasing, cheerful behavior no matter what.
The example in the series, however, is Hungary. Shown clearly not just in the profile, but in her interaction with pretty much everyone: she takes her Meido position in stride despite how it's not exactly easy, fights the aforementioned Prussia without hesitation, refuses to stay put when someone she dislikes is around...
I Had That Same Dream Again: Nanoka has a bit of an attitude problem and tends to look down on her classmates for not seeing things like she does, but on the whole she is optimistic, courageous, and tries her best to help and encourage people.
Hikari no Densetsu: Hikari is determined to be an Olympian no matter what, and trains rigorously for the day she'll get to fight for the World Cup. Her inspiration is the Real Life celebrity Diliana Georgieva, who rose from an ordinary woman to being one Bulgaria's greatest athletes.
Isabelle of Paris: Even though she's under house arrest and suspected of being a traitor, fifteen-year-old Isabelle Laustin becomes a double agent for France and rebels against the government by shaving her head and becoming a spy. She even has the audacity to walk up the Captain of the French military and Bitch Slap him.
Kagome Higurashi has got self-esteem problems, is the reincarnation of a priestess who Came Back Wrong, her love interest can be a real jerk despite having a good heart, her friends have huge troubles of their own... and yet she stands by them no matter what. Sure, she has more than one breakdown, but she still stands by her friends and is more concerned with her love life and her grades.
Rin may not be much use in a fight, but let's face it, she's brave as hell. Heck, the first time she meets Sesshomauru she doesn't run screaming when he snarls at her but actually dumps water on him; and when Jaken's sick she climbs a mountain filled with demons to find a cure for him, without a second thought.
Jeanie With The Light Brown Hair: Jeanie. Diana won't let her go to medical school? She argues and convinces her to agree. The children at the orphanage play pranks on her and don't trust her? She pranks them back and impresses them, and they become her friend. A child goes missing? Jeanie convinces everyone to help find them using betting money as a reward. No matter what obstacle appears, Jeanie is ready to throw herself at it and win.
Sora Naegino practically embodies this trope. No matter how much Training from Hell she is put through or what sort of abuse she receives, she always manages to pull through using sheer optimism and determination. And if she feels her strength sapping away, she will soon recover it. It's also kind of a plot point, as if she stays down for too long, she will stop seeing Fairy Companion Fool and completely lose her chance.
May Wong becomes this once she gets over her Jerkass phase. Anna Heart, Mia Guillem, Rosetta Passel and Katie Taylor are already there, and the backstory gives us Sophie Oswald.
Nanami Momozono from Kamisama Kiss. Her defining character trait, besides Chronic Hero Syndrome, is that she likes to see other people happy and will go out of her way to make them happy. Even if it means that she has to get hurt or sacrifice something to make it so.
Katri, Girl of the Meadows: Katri Ukkonemei is a headstrong Finnish girl who's strength inspires others. She never learned how to read, so she taught herself by constantly visiting Palki Village's library, and works her way into getting a scholarship despite being a mere Farmers Girl.
While Ryuko Matoi from Kill la Kill is more of a female Determinator, her Only Friend Mako Mankanshoku is this through and through. She always comes out of any situation with a smile on her face, no matter what. She's pushed to her limits when sharing a stand with the demoted Elite Four while cheering Ryuko on during the King of the Hill Final Battle, resorting in her cheering for herself so she won't crack under the pressure.
Madoka Kyouno from Lagrange: The Flower of Rin-ne, going so far as to sing in the cockpit during a mecha battle... the same battle in which she deliberately tries to keep collateral damage to areas she knows to be empty of bystanders (such as the lot of a recently demolished house or a shop that had gone out of business the week before). Considering the genre she's in, she angsts remarkably little - and even when she does, she shrugs it off quickly and jumps right back to the other extreme on the optimist-realist scale. It is later revealed that she wasn't always like this: after her mother's death, Madoka was a depressed wreck until her cousin inspired her into the energetic girl always ready to help everyone regardless of what needs to be doing. Truly, Madoka's motto in life is Jumped at the Call: she doesn't pilot because she has to, she pilots because she wants to help.
Lady!!: In spite of her mother's death and her grandfather refusing to accept her for being half-Japanese, Lynn strives to be accepted in the Russell family no matter what. Initially, she was broken by learning her father would formally marry her Wicked Stepmother and tried to escape back to Japan to prevent it from happening. When her father asks that she stay and breaks it off, Lynn works on being accepted through her own merits - and eventually does when she wins the Lady's Crest and represents Great Britain in the Olympics, even saving the Russell family house thanks to a bet she made with Victor Reynolds. Finally, her grandfather accepts her.
Simone of La Seine No Hoshi is just a peasant girl (or so she thought), but from studying under Duke de Forges, she becomes a vigilante that kicks the tar out of France's corrupt elite regularly. She ignores the mob telling her that she's unfit for the job because she's a woman, and becomes a celebrated icon in France.
Lakshu from Legend of Heavenly Sphere Shurato. She can't fight, the Goddess/mother figure she's a priestess of is Taken for Granite, her crush and her friends get hurt and/or die as they try to restore her... and Lakshu will help no matter what.
Lucy-May of the Southern Rainbow: Lucy-May is this constistently. Arthur says she can't have a dingo unless it's trained? She domesticates it. She can't speak to Hercules because of the Language Barrier? She communicates non-verbally. No matter what problem she faces, Lucy-May always tries to solve it.
Macross Delta: Freyja Wion. Even her homeworld declaring war on the rest of the galaxy (indirectly exiling her from it), being involved in the middle of multiple war zones as part of her career, and finding out her love interest's father bombed her homeworld ultimately do not stop her from pursuing her dream to sing with the idol group Walkure, even if they do take her aback, and she ultimately holds her energetic personality and kind heart to the end.
She follows her predecessor, Ranka Lee, in this regard. While Ranka is significantly less energetic, she is no less determined to be an idol and pursue her dreams (and her love interest Alto), even despite her Dark and Troubled Past and frequent setbacks.
Sayaka Yumi from Mazinger Z: Her mother was dead. Her father cared for her, but he was Married to the Job and nearly never was there for her. the guy she liked was a sexist jerk (okay, Jerk with a Heart of Gold). One of her classmates was a borderline Stalker with a Crush. And her country -and the whole world- was under attack of a Woobie, Destroyer of Worlds and Mad Scientist who took lessons from Hitler. And she still was brave, hopeful and optimistic, not allowing anything got her down for long -she had several Heroic BSoD moments, but they did not last long-, and trusting they would win and things would get better, not matter what.
Relena Peacecraft, Hilde Schbeiker, Sally Po, Cathy Bloom, Long Meiran and Lucrezia Noin from Mobile Suit Gundam Wing. All of these young women knew they were getting into huge messes, and that they'd likely not get out of there alive (and Meiran ultimately died), but neither gave up on their purposes.
A dark example is Nena Trinity. While throwing the V-Sign around, she absolutely refuses to give up her quest for three things: revenge, survival and (after achieving those) happiness, even in the face of death. She doesn't succeed, as her early screw ups catch up with her.
A lighter example is Mileina Vashti, almost always plucky and happy despite being caught in the middle of a war. She lives to tell. Also Mileina's Onee-sama and fellow bridge bunny, Feldt Grace. She gets very broken in season 1, then some more in season 2, but also pulls through and lives.
Ochaco Uraraka from My Hero Academia was deliberately written this way in order to have a more natural relationship with the more pessimistic and self-conscious main character, Izuku Midoriya.
Hinata Hyuuga. Her other theme, aside from her nice, gentle personality and her love for Naruto, is her self-improvement and shredding her Shrinking Violet side. She's one of the first people to adopt Naruto's ninja way: knowing that he's watching, she refuses to give up against Neji despite severe injuries, even standing up one last time after the referee ends the match to keep her from getting killed. She reaffirmed her pluckiness by doing what she could to protect Naruto from Pain, fully knowing that this might be her last stand. The manga made it both awesome and heartbreaking, the anime made it doubly awesome and doubly heartbreaking.
Also Sakura Haruno. See her fights vs Ino (where she deliberately pressed Ino's Berserk Button to avoid getting sympathy and broke Ino's Mind Switch Jutsu, albeit with a little help from Naruto's cheering) and Sasori (where she got serious injuries and kept fighting anyway).
Many girls from Negima! Magister Negi Magi qualify, but Nodoka surpasses them all. Every time she's encountered an enemy, despite having no combat skills whatsoever, her first reaction is to get out her artifact and fight, even when up against opponents completely out of her league, even when everyone else is panicking, lost in despair, or running away, even when she only just figured out that magic even exists. In the middle of the battle between Fate's party and Ala Alba at Ostia instead of retreating with the rest of the party she forced Kotarou to take her right in front of Fate so she could get his true name and then interrogated him as he was attempting to petrify her. And of course, when everything went wrong and several of her friends were erased from existence right in front of her by one of the most powerful characters in the entire series she gets up, steals HIS artifact, downloads the instruction manual from his brain, and teleports away so she can tell the rest of Ala Alba they're taking the battle to the enemy.
Nami despite her horrific childhood and being a Damsel in Distress on occasion has displayed Plucky Girl qualities since she was little and is still highly adventurous and bold as a grown woman. Even when Overshadowed by Awesome she’s proved be invaluable and supportive crewmate even when the Straw Hats have suffered a humiliating defeat such as in Water 7.
Vivi’s greatest trait is her nigh-unbreakable optimism and pluck even when faced with the massive threat of criminal organisation ripping her country apart from within. Her wild bravery has freaked out her guardian Igaram (who fears Vivi will become a pirate) and inspired her friends the Straw Hats to save her country.
Kaya, after having spent an arc Delicate and Sickly recovers and journeys out of her village determined to become a doctor, inspired by Usopp whom she adores.
Deconstructed with Tashigi who is a Plucky Girl, but this attitude gives her the terrible habit of picking fights with people that are way out of her league, especially ones such as Robin or Law, who have powers that easily render Tashigi's own abilities useless.
Ringo Oginome and Masako Natsume from Penguindrum. Himari graduates into this on episode 18, which also shows us exactly how indomitably plucky the deceased Momoka was.
When told that the boy who rescued her two years ago has gone missing (and hasn't seen since), Yellow immediately agrees to go out and look for him despite the fact that she barely knows anything about Pokemon battling.
Green could also count. She's usually upbeat and optimistic despite having some of the worst luck ever. Especially at the beginning of the FireRed/LeafGreen arc, where her parents disappear right in front of her (though that trauma does give her a Heroic BSoD for a while).
Tomoka Osakada from The Prince of Tennis never ever loses her smile, her stubborness, and her will to support Seigaku and her beloved Ryoma through thick and thin. An Tachibana from Fudomine is somewhat more serious, but she's not to be trifled with either.
Sayaka Miki. Shame that it's that kind of world, as it doesn't end too well for the poor "hero of justice". Fortunately for her (and many others), in the Grand Finale Madoka graduates to one... and is so powerful and strong that she rewrites the universe itself, and grants Sayaka a much more peaceful end.
Hitomi Shizuki is referred as such by her seiyuu Ryōko Shintani, as well as by Aoi Yūki (Madoka) and Chiwa Saitō (Homura). She's an interesting example in how this trope has both strengths and flaws: she always smiles and tries to be there for her friends, but the time Hitomi tries to directly resolve a conflict via making both Sayaka and herself face their shared feelings for Kamijou, she commits a huge mistake.
As opposed to the main series, Sayaka does get to play this straight here, especially via protecting herself and Hitomi during the witch attack on their school. Too bad they can't save Madoka.
Pollyanna: Pollyanna Whittier is determined to remain a Blithe Spirit no matter what, and invents The Glad Game to keep her head high in the face of whatever life throws at her. And boy, does it throw a lot.
Ranma ½: There was a time when Ukyo wanted vengeance against Genma Saotome for renegging on his promise to wed her to Ranma, by abandoning her. And despite having caught up to them (years later), she's no closer to achieving her goal of becoming Ranma's bride. You'd think she'd be crushed, but she's actually... kinda okay with it. After all, he calls her "his cute fiancee" and she gets to attend class with him. For her, it's a start. In the meantime, she runs a successful business and tries to think of mostly nonviolent ways to absolve Ranma's engagement to Akane, by trying to pair Akane off with Ryoga.
Kiku Takane from Ring ni Kakero, who will always support and look after her little brother Ryuuji and work hard to guide him through their shared dream of reaching the World Boxing Championship.
Juliet Capulet from Romeo × Juliet who has more moments of Break the Cutie than her play counterpart. The poor girl's parents were killed when she was both dethroned and forced to be a Noble Fugitive at a young age, forced to dress as a boy most of her life, then being shocked and unprepared as she remembers her parents' death was forced and expected by her guardians to lead a revolution when she's not ready to. And to top it all off, she falls in love with the son of the man who killed her parents and though she has a moment of giving up and wishing she was dead she still retains her sweet lively fiery and lighthearted personality and is eventually ready to lead a revolution.
The Sacred Blacksmith has Cecily, who in the anime, despite losing and needing saving a lot, never stops practicing and fighting.
Cleao Everlasting from Sorcerer Stabber Orphen will not let Orphen go kill himself before he returns her the Sword of Baltanders that her father gave her before dying, and which he needs for a very important quest. So what if she has to tag along with him and his apprentice Majic despite all the dangers it'll bring to her? She will follow them, become the Team Mom, and pull through no matter what.
Ai from Sunday Without God is brave, optimistic, and determined, and she goes out her way to help those in need. Of course, since she's resolved to save the world God has abandoned, this is the attitude she needs.
Pao-Lin/Dragon Kid and Karina/Blue Rose. Dragon is a headstrong Little Miss Badass who goes all out in superheroing; Rose hates the raw deal she got as a heroine but keeps going on because it lets her save lives.
As of episode 21, Kaede Kaburagi has graduated into this. So her beloved father was framed and she has just found out he's a superhero? Kaede immediately decides to go help him with her budding powers. And this is a ten year old girl.
Several girls from Vampire Knight - specially Yuuki, Yori and Fuuka before she dies.
Wandering Girl Nell: Nell is a little girl who's sure that she knows what's best in spite of what adults say. Seriously, Brass gets an earful from her when he proposes that she becomes his wife.
Keiko Yukimura from YuYu Hakusho. While she's usually a Neutral Female, it's pretty amazing she pulls through after all the traumatizing events her boyfriends' life/career puts her in. In the manga, she didn't hesitate to ask to be taken to the Dark Tournament when she found out Yusuke had gone there. She may be a bit frailer in the anime, but she still does her best to be there for her friends when needed. To different degrees there's also Yukina, Shizuru, Botan, Ayame, Hinageshi from The Movie, Kokou, Natsume, the Lady Doctor aka Yuusuke's ancestor and Mukuro.
'Poi' means "poof," and it's used in-context as "making problems and bad luck go POOF!"