Toge Sohei from Adolf is 28, but looks like he's in his sixties. He even has grey hair in the colour illustrations.
After War Gundam X (which used the same animation studio as Wing) has Roabea and Witz, the Freeden's standing mercenary contractors. Both of them are a good foot taller than 15-year-old protagonist Garrod, frequently call him an impetuous youth, and Roabea particularly has a world-wise attitude and a tragic Lost Lenore. From all this plus their facial features, you'd guess them to be in their late twenties, but they're both eighteen.
Akagi: Shigeru is only 13 pre-Time Skip but looks considerably older in the anime (he's more plausible in the manga). A line referring to his age was even changed from "Yeah, you look it too" to "Really? You don't look it" in the adaptation.
In AKIRA when a Juvenile Corrections Officer is lecturing Kaneda and the gang on their behavior, Kaneda calls him "gramps" as an insult, the man tells him he's only 25, he appears to be in his mid 30s-early 40s.
Mr. Mustachio from Astro Boy appears to be around 60-years-old with his white hair and mustache, but on one occasion a villain calls him an old man and he tells him he's only 42 and that he looks older because he went bald early.
Attack on Titan has Zeke Yeager's official age being listed as 27, although he looks much older. This seems to happen to Titan shifters, as Reiner also arguably looks older than 21. Uri Reiss suffered from this as well, and although we don't know how old he was, in flashbacks he looked a lot older than his brother Rod does in the current story. The very extreme ageing could be a side effect of being a member of the royal family who's a shifter, but the exact nature of it has not yet been explained. The fact that Titan Shifters only live for thirteen years after gaining their powers may also have something to do with it.
Azumanga Daioh features a strip where high schooler Tomo expresses jealousy at how her classmate Yomi gets mistaken for a college student or secretary by passersby, while she herself often gets mistaken for a middle schooler. Likewise, fellow classmate Sakaki looks around as old as her teachers— who are in their 20's— thanks to being a Huge Schoolgirl.
Baby Love:
Seara is around twelve and is an elementary schooler however looks older. She is a Huge Schoolgirl and in-series can pass for a middle schooler with little issue.
Seara's crush Shun is a middle schooler but is said to look like a college student.
Bakemonogatari features the Vampire Hunter Episode, who looks and (mostly) acts like he's in his late teens. However, he ages unnaturally due to his nature as a half-vampire. In reality, he is only 6-years-old.
Shogo Kawada should only be around a year older than his 15-year-old classmates but he looks much older due to his muscular physique, long facial scar and thick stubble as well as his mature demeanor. Possibly a Justified Trope as he was forced to mature quickly in his first entry into the programme and his childhood helping his father in ..
Mitsuko Souma has a very mature figure for her age and wears thicker make-up than the other girls, both of which she uses to her advantage in The Program, like Kawada, her appearance is also probably justified by her childhood trauma as a victim of sexual abuse.
Guts could be mistaken for a guy in his 40s because of the physical and mental stress he's endured, but as of the Fantasia Arc he is only 24-years-old, Casca is the same age as Guts but she looks almost a decade younger.
Pippin is a even better example, the The Big Guy of Band of Falcon looks like he's in his late 20s to early 30s, but at the time of the Golden Age his actual age was 19. For contrast Corkus is a year older than Pippin despite looking younger,◊ though the movie adaptions make Corkus look closer to his age.
The King of Midland's age is never precisely stated, but for most of the Golden Age arc, he looks like a well-preserved man on the upper end of middle age (which lines up with his daughter Charlotte being somewhere around her late teens), and the official guidebook claims him to be 53 at the time of his death. However, after Griffith sleeps with his daughter and he goes insane, the stress causes him to age rapidly. Just a year later, he could have easily passed for a hundred-year-old man.
In Big Girl and Small Girl, the main character, an adult woman who looks much younger than she actually is, meets a tall and somewhat well-endowed girl at a pool. It's clear that the other girl is young, since she calls the main character "Onee-san,"note Not only a way to address an older sister, but also what children call young women, but doesn't realize how much younger the young girl is until she sees her carrying an elementary schooler's backpack.
Pinoko of Black Jack depends on how you count it. She started life as a teratoma (a form of tumor) that had grown everything but a body while attached to an 18-year-old woman. If you count her life starting with her "sister", she's eighteen and Older Than They Look; if, like Black Jack, you count her life from when she was removed, she's less than a year. Either way, her artificial body looks about six.
Sawatari, one of the Bounts. It's a weird case because Bounts can live forever as long as they have souls to devour, but despite Sawatari looking like a very old man he's relatively young for a Bount. He looks so old because he ate too many souls when he was younger, which caused his body to age at an accelerated pace.
Sado "Chad" Yasutora looks to be in his mid to late 20s despite only being 15, largely because he towers over most adults (being almost six and a half feet tall) and is built like he wrestles bears for a living.
In Bludgeoning Angel Dokuro-chan, the title character has a 9-year-old sister that looks about nine years older than her.
Cleo from Broken Blade is only slightly shorter than most of the other female characters, and still manages to rival them figure-wise. Would you believe she's 12? The other characters certainly can't.
Downplayed in Bubblegum Crisis: given how long ago sexaroids were labeled as illegal by the series start, we get the implication that while Sylvie and Anri may not be as old as they look (Sylvie appears in her mid-twenties while Anri looks to be the loli model), they're not single digit ages.
Hiroshi Agasa of has fallen victim to this. He dislikes being called "ojisan" since he's only 53-years-old.
Hyoue Kuroda is three years younger than Agasa, but looks even older. This is mostly because (like Agasa) he's fully grey, and also has very weathered skin, both a direct result of a severe accident that left him comatose for a decade.
Stiyl Magnus. You know, this red-haired guy who's smoking all the time and is about two meters tall. Believe it or not, he's just 14. This is actually a result of a miscommunication between the writer and the artist. The writer said that Stiyl's battle with Touma was meant to be "old vs new" meaning magic vs science. The artist read that, missed the note after about Stiyl's age, misinterpreted it to mean "old man vs young man" and drew Stiyl as a man in his 30s.
Kanzaki and Oriana also looks around 20-25 when they're both only 18.
All of the Misaka clones, naturally. Most noticeable with Worst, who looks older than the rest (including older than her original), but is actually the youngest clone. She is teased at one point that, despite looking 16, she's technically the "younger sister" of Last Order, who looks 10.
Misaki Shokuhou, the fifth level 5 esper, looks like a buxom college or high school girl, but is actually in middle school. However, since her power is Mind Control, it's theorized (both in-universe and out) that she is actually as old as she looks, but she's just using her ability to make everyone think she's younger than she really is. Turns out she is in fact the same age as Misaka and a year before the series began, was as developed as her fellow level 5. Talk about puberty being unfair.
While Satella of Chrono Crusade looks somewhere around her late twenties or early thirties, she turns out to only be 19-years-old much to the surprise of Rosette.
Jet of Cowboy Bebop looks like he could be in his forties or fifties, but is only thirty-six. This is lampshaded in the preview for "Waltz for Venus" when he tells us this, and says you shouldn't judge people by how they look, or how much hair they have.
Anna Yamada of The Dangers in My Heart is physically more developed than girls her age, is at the height of the average Japanese adult male at 171.9 cm, works part-time as a model/actresses, and gets type-casted as a high-school girl. She looks like a young adult (especially when dressed out of her school uniform), but she's really a 2nd-year middle schooler (13-14).
Yukio Oikawa of Digimon Adventure 02 would be in his early thirties, but you'd never know that by looking at his grey skin and sunken eyes.
Marcus Damon and Thomas H. Norstein of Digimon Data Squad look to be in their late teens, and seem not much younger than their teammate Yoshi who's 18, but are both actually 14.
One of the students in Doki Doki School Hours looks and acts like a middle-aged man even though he's still in high school. They even call him "Oyaji" (i.e. "Geezer" or "Pops").
You would never, ever know it by looking at him or hearing him talk, but Piccolo at the beginning is chronologically only 8-years-old. Nobody remembers this, for good reason. When he was born he was supposed to be a demon. He actually takes much longer to reach maturity than Piccolo Daimaou's other "offspring", who are full-grown when they hatch. Especially amusing in retrospect when he's teaching Gohan who is only a couple years younger than him at 4-years-old.
Cell is much, much younger than you'd expect — even with all the time-traveling he had to do to reach a timeline where he could absorb the Androids, he's still only in his early twenties.
In Dragon Ball GT, there is an extreme case of this in the Shadow Dragons, who, though mature as any other Dragon Ball villains, are, by technicality, newborns, spawned from the Dragon Balls' misuse. GT also gives us Bra/Bulla, who's only 11 but wears revealing clothing and looks a few years older — to the point where grown men hit on her. In front of her father. Who is Vegeta. It goes about as well as you'd expect.
The antagonist androids of Dragon Ball Super: Super Hero Gamma 1 & Gamma 2 and Cell Max despite looking like adults were only created shortly after the new Red Ribbon Army hired Dr. Hedo (a day at most), meaning even little Pan who’s 3 years of age, is older than them.
George of Dragon Crisis!, despite looking about thirty, actually turns out to be 19.
Dungeon Friends Forever: When Sylvia offers Golde comfort after fighting Van, the Board of Directors get up in arms about how Golde can get a young girl like Sylvia giving him such affection. They're shocked when Sylvia explains that not only are they married, they're both the same age.
Board of Directors: That age gap is way too much!! Sylvia: What? No, we're the same age. The same age. Board: Huh? Sylvia: We're both 35 years old. Board: So young!! Golde/Sylvia: We get that a lot.
The silpelits from Elfen Lied age at about double the rate of normal humans. Nana looks 14-15 and is really around 7-years-old. Similarly, Mariko is really somewhere around 3-years-old.
The Elusive Samurai: Ayako is a head taller than Tokiyuki, so she can easily pass for a teenager and is often mistaken for one by several characters in the series. However, she is the same age as Tokiyuki and everyone else in his squad. Keep in mind when they are first introduced they are eight-years-old.
In Excel♡Saga, a paedophile takes a 9-year-old to a love hotel, only to learn that she's, er, "prodigious."*She was able to completely hide away her triple-g cup breasts. The episode in question was making as many jokes that couldn't be aired on TV as possible (it didn't, which was what the creators wanted), but everything was still played for laughs (all black laughs), which meant the paedophile left the underaged girl broken-hearted when he saw what she looked like, before anything awful happened.
The one that takes the cake is Rikiya Gaoh: He's two meters tall (6'7"), square-jawed, musclebound, capable of bench-pressing over 200 kg (over 440 lb)...and we're supposed to believe that he's a high school freshman. Some of the other characters don't believe it either ("There oughta be a law against players like him!").
Atsushi Munakata of the Amino Cyborgs, whose tremendous musculature and broad, dashingly handsome face make him look over 30, a fact that is actually commented upon. One Omake chapter shows that he actually looks exactly like his father... and his mother.
Lampshaded when Sena and Monta discover the identity of Musashi, who they only knew as the middle-aged looking construction guy who worked on their ever expanding clubhouse. They cry out in unison "You're seventeen??!!"
Similar to Musashi, Yamabushi from Shinryuuji looks much older than he is due to his half-grown in beard. He's even charged with pumping up the Japanese youth cup team before the game against America because he looks the oldest. When he gets too emotional, the similarly adult-looking Mamoru Banba steps in to offer his own uplifting words.
Mr. Don, Gaoh's opponent in the American game, is supposed to be 18, but looks closer to sixty with his white hair, massive stature, and heavily-wrinkled face.
Lampshaded in a chapter where we learn they even have rankings for who has the worst case of "old man" face.
First Love Monster gives us Kanade Takahashi, a fifth-grader with the body of a 17-year-old. Given the series' genre, the heroine finds it awkward to be dating him. Don't worry though — he's not alone in his affliction, as two of his playmates are also young boys who look like grown men.
Ling Yao of Fullmetal Alchemist is a mild case. He's 15, but he looks like a fully-grown adult. This is used for both a joke about him being much taller than Ed (who is slightly older) and a plot point when he's arrested as an illegal immigrant and the authorities don't believe he's really a minor.
Suzumura from The Gods Lie is an 11-year-old elementary school student who towers over the other kids.
Azumane Asahi is tall, broad and has a stubble which makes him look older and more intimidating than he is. There are even rumours going around in Miyagi high school volleyball teams that he had been hold back five years in high school. He's been mistaken as a teacher and more than one occasion, as a 30-year-old man.
Downplayed with Kageyama. While he does not look much older than his age, he is always with Older Than They Look Hinata who is actually half a year older than him. Kageyama is actually the youngest member of the team, as he is a first year who was born in late December.
Yuki Nagato and her associates appear to be about fifteen, but as constructs of the Data Overmind, their physical bodies at least are only up to 3-years-old. It's somewhat debatable since it isn't known how the whole system works, but with Nagato getting trapped in a time loop for hundreds of years (and mentally aging, as she alone retains full memories of the repetitions) the fifth novel inverts this and makes her Really 700 Years Old. An alternate theory mentioned in the show is that the whole universe was recreated three years earlier, so everyone who thinks they're older than three is actually Younger Than They Look.
Kyon's sister's friend Miyoko is this. She is the same age as his elementary school aged sister but appears to be within a year of Kyon's age.
It is revealed that Maria in Hayate the Combat Butler is only 17, but she is incredibly mature and everybody mistakes her for a beautiful woman in her mid-to-late-20s, leading Hayate to believe that he Likes Older Women. It also becomes a Running Gag that Maria is irritated when people mention "young girls" as if she doesn't fit into that group. Specifically, she keeps saying "I'm 17-years-old" with increasing irritation. It's also a Shout-Out to Kikuko Inoue.
Hellsing: Despite looking like she's in her mid-thirties due to her toughness and no-nonsense behaviour, Integra is a young woman of 22.
Hibiki's Magic has Asuma, a wizard who ages much more quickly than normal as a price for using magic. In reality, he's probably at least in his late teens, but he looks to be about in his late 20s/early 30s.
Leorio of Hunter × Hunter looks like a businessman in his thirties or early forties. He's nineteen. It was even lampshaded when he tells Gon and Killua, who are more than shocked.
Inuyashiki: Ichiro Inuyashiki is 58, but he looks about two decades older than that. His daughter Mari is always embarrassed when people mistake him for her grandfather.
Harumi appears to be in her mid-twenties, but viewers who have a quick enough eye to catch her character stats just before the commercial breaks will be surprised to realize that she's only 3-years-old. It turns out that she's an android, so don't worry too much about it.
A more mundane example in the same show would be Dr. Kitaguchi, a 33-year-old doctor who looks like he's somewhere in his 50s. If his self-proclaimed thirty-year drinking habit isn't an exaggeration, you can probably figure out why.
The first big example is Jotaro Kujo in Part 3, who does not look like he's 17. Due to Art Evolution, he ends up looking younger when he appears in Part 4 and Part 6.
From Part 3, Avdol looks like a middle-aged man, but while he is the second oldest of the main group after Joseph, he's only in his late twenties.
The same applies to a lesser extent to Josuke Higashikata and Okuyasu Nijimura in Part 4, who look significantly older than teenagers who are just starting high school.
Part 5 has Giorno Giovanna and Trish Una. You'd think they'd be both adults, considering they both look as old as the more experienced members in Passione. Nope, they're both 15, and the one person on the team who actually looks like a teenager, Narancia Ghirga, is two years older than them due to malnutrition.
Lucy Steel from Part 7, despite her height and figure, is only 14-years-old.
Gareki from Karneval looks to be in his early twenties but is actually only 15. He often acts more mature than 21-years-old Yogi and is also a guardian/big brother to Nai, all of which only strengthen this impression. The implication is that his very harsh childhood forced him to either grow up fast or perish.
Subverted in Kill la Kill — despite being a high-school senior, Ira Gamagoori doesn't look like he could realistically be in his teens... Because he isn't. It turns out that he deliberately put off leaving middle school for a couple of years so that he could be in the same year as (and thus serve under) Satsuki. He's not that old though. He explains he's turning 20 of that year. Meaning he's 19 during the series proper, basically in his late teens.
Mako: That explains the old-man face!
Kuroko's Basketball: Some players look way older than highschool boys. Exaggerated by Team Jabberwock, a team of American 18-year-olds who look like they in their late 20s or early 30s.
In The Legend of Zelda: Twilight Princess (2016), Link starts off looking every bit the teenager he is, but the weight of his journey ages him quite noticeably. By the time he enters the Twilight Realm to battle Zant, he looks to be in his mid-twenties rather than his late teens, which Darpa teases him for when they reunite.
Daisuke Jigen from Lupin III he looks like he could be in his 50’s or 60’s and has a gruff, gravely voice, which could be attributed to his chain smoking, he often acts as the father of the group, and besides Goemon is one of the more mature members of the gang, he’s only around 36 years old and only a few years older than Lupin.
Arf is another example. She looks to be in her mid-twenties or so, but in reality is probably only 3- or 4-years-old tops considering Fate created her, and Fate herself is another example as a clone with a copy of the memories from the girl she was cloned from.
By extension, this trope applies to Erio and Zest for the same reasons as Fate.
Sette looks like an adult woman, but is the last of the Numbers to have been activated, and thus younger than any of the others (particularly Cinque, who is a direct inverse: looks like a kid, has the mind and skills of a seasoned commando).
Mikumo Guynemer from Macross Delta appears to be the most mature member of Walkure. However, she is actually only three years old, being an Artificial Human engineered from the Star Singer's remains.
Mahoromatic, being about androids, has an alien android who poses as a school teacher. When asked over the course of the series about age-related issues, such as if he would go drinking with a group of other teachers, he always replies, " That would be illegal, as I am only 3-years-old." For some reason, nobody bothers to question him on this.
Noguchi from the March Comes in Like a Lion, who is a highschooler despite sporting a thick mustache. Lampshaded in the first chapter he appears in with notes constantly pointing out that he's a 2nd-year.
Kōran guesses Shiki to be 21, seeing as he is mature in both appearance and personality. His actual age? 17. Yes, he's younger than her.
Which naturally makes his younger brother Rinshō qualify. It becomes real scary considering all the horrible things he's done…
In Mission: Yozakura Family, Nanao Yozakura is a first-year high school student, but his genetics make him look like a hulking, three-meter tall man. It's actually Played for Drama when it's pointed out that a three-meter tall high schooler would draw heads, forcing him to develop a drug to shrink himself down to a normal size. And when that drug stops working, it will mean that he won't be able to attend school or college the way he always wanted to.
Nearly the entire cast of Mobile Suit Gundam Wing look older than their official ages. Most of the enemy pilots look and act as if they're in their 30s, but are instead late teens or early 20s. The 5 protagonists are all 15, but look to be in their late teens to early 20s. Pretty much the only characters given an official age who actually do look and act that age are Catherine Bloom (17, the sister of one of the protagonists) and Sally Po (26, a resistance fighter).
In Modern Magic Made Simple, Yumiko easely look like she is in her 20s, so Koyomi is surprised to learn that she is the same age as her, 15-years-old.
In Monthly Girls' Nozaki-kun, the eponymous Nozaki's tall height and muscular build makes it easy to forget he's an eleventh grader. Kashima's sister is convinced he's an adult, first mistaking him for a teacher and then for the school's groundskeeper. She later tells her sister off for talking impolitely to someone "8 years her senior", which naturally annoys Nozaki to no end.
Takeo from My Love Story!! is only a high school freshman but is a huge, gonky looking boy with a very deep voice. This has made many people mistake him for an adult. This causes even more problems because his girlfriend is very petite and young looking. They've been mistaken for father and daughter at least once. Takeo has even been mistaken for his mother's husband.
Tsunade manages to be both this andOlder Than They Look: in calendar years, she's about fifty or sixty, the same as Chivalrous Pervert Jiraiya. However, she uses a powerful genjutsu round the clock to make herself look like a 20-year-old (or however old she needs to be to escape her creditors.) However, her most powerful jutsu of her own invention heals any wound she may receive, but at the cost of aging her far faster than her contemporaries. So without the genjutsu, she is younger than she looks. (whew!)
Teuchi, the ramen shop owner, appears to be in his 60s at best but is only 43 at the beginning of the manga.
It's implied Kakashi was 6 when he became a genin but he looked indistinguishable from even the current cast, who were 12 when they became genin, Kakashi keeps this trope going as an adult as he looks like he's in 30s with his white hair but was only 26 when Naruto was genin. Lampshaded as Kakashi was quite upset when a little boy and girl (Naruto and Sakura in disguise) called him “old man” after rescuing their cat.
Asuma with his beard looks much older than his actually age of 27 at the start of Naruto. Amusingly his spouse Kurenai was 28 at the time making her a year older than her husband and two years older than Kakashi despite looking like a teenager compared◊ to them.
Can't forget Might Guy who is the same age as Kakashi (26) despite looking 40-something, it's not until Boruto that any of the Jonin look their age.
Two of the Huge Schoolgirls are forced to pay full price for movie tickets, even though they're only 14- to 15-years-old (while two of their classmates who are a couple months older but look younger get away with claiming to be elementary school students for a larger discount). One of them gets so mad, she uses magic age-reducing pills to turn herself into a small child, until she realizes (too late) that the cost of the pills combined with the ticket come out to more than she would have had to pay normally. The other, being a Ninja, just Henges herself younger for free.
There's Chachamaru, who has been built two and a half years ago, but looks like a teenager.
Naba Chizuru is explicitly the youngest girl in the class aside from the android but is maternal enough (in multiple senses of the word) to pass for at least 20.
In Neon Genesis Evangelion, it's implied that Rei is in fact a 4-year-old with the mind of a 14-year-old as a result of being a clone. On the other hand, there's no evidence the clones haven't been growing at a normal, human rate, so physically they could all be 14. It all depends on how you interpret what counts for age: mind, body, or soul? How much are Rei I, II, & III the same person?
Shinonome Nano from Nichijou looks and acts like a high schooler but she is actually only a year old at the beginning of the show. She's a robot (with a wind-up key, natch).
Mireille Bouquet from Noir looks to be somewhere in her mid to late 20s, but the timeline of the series suggests she's actually only around 19-years-old. Given that she seems to have been working as a professional assassin for some time before this it leads to some Fridge Horror.
Hotaru from Non Non Biyori is only in 5th grade but is taller and bustier than her middle-school aged peers that she's constantly mistaken for a college student, or even an adult.
Hana-chan in the final season of Ojamajo Doremiafter she aged herself magically from a baby to a tween.
This trope applies to Zoro and Sanji at the start of the series, who thanks to appearance, personality and being voiced by older male voice actors; seem much more older and mature than their actual ages of 19. It's especially amusing as Zoro The Alcoholic wasn't even old enough to drink at the time (legal drinking age is 20 in Japan). Sanji seemed older to some fans (probably because he smokes), as in a SBS they questioned Oda about Sanji's offical age thinking he was lying; leading Oda to say they have to take his word for it.
Vivi as Miss Wednesday looks like she's in her 20s, so may come as a shock to learn she was only 16 at the time. This may be part of her The Reveal that’s royalty as she even has a different voice actor when disguised. After dropping said disguise, she is drawn looking more closer to her actual age; though she's still as bosomy as Nami so this trope is still in effect.
Kaku is a In-Universe example as he speaks like an old man, leading to Usopp and Nami questioning his age. Kaku answers that he's 23, only a couple of years older than them. Rob Lucci is also a good example, as he looks as old as Jabra (who's 35) but is actually 28, he just seems older due to his extreme seriousness and brutality.
Kalifa is drawn looking more mature and older than Nami, though she's only 6 years older (at 25-years-old) and is younger than Robin (who was 28 at the time).
Mermaid Princess Shirahoshi is in the same boat as Vivi: despite having the upper body of a grown woman she's only 16. For additional irony, she's massive as well. Though it's also worth mentioning Shirahoshi acts like she's even younger, crying frequently and whining, due to her mother's death and her sheltered upbringing.
Oda pulls this a third time with a princess: Rebecca◊ from Dressrosa. Her Chainmail Bikini shows she's as developed as Nami or Robin but in actual fact... she's also 16, making that getup an Age-Inappropriate Dress. Pretty ridiculous when she looks the same age as her aunt Viola who is freaking 29.
Pudding, the 35th daughter of Big Mom. She's as curvaceous as Nami, but the introduction of her younger sister (who's 15) threw her age into question. This was corrected on the day of the chapter's release by Oda's staff on Twitter and on a later chapter, but even with the correction Pudding can't be any older than 16 or 17. This would've made her relationship with Sanji a May–December Romance had it actually happened (but it didn't).
"Glutton" Jewelry Bonney is introduced looking like a woman in her early- to mid-20s, but Oda specifically gave her a Vague Age to hide that she's actually 12, and uses her Fountain of Youth powers to appear older than she actually is and thus hide from the World Government. Her true form is a conventionally small and cute preteen, which is revealed when the Straw Hats fish her out of the ocean and her Devil Fruit powers are disrupted.
Taeko Okajima the main character from Only Yesterday, due to the wrinkles and lines in her face in some scenes she looks like she could be in her 40s or 50s but she's stated to be 27.
Ōoku: The Inner Chambers: Aonuma is only in his 20s, but people constantly mistake him for a 30-year-old.
Otaku no Musume-san: Taeko, a high school student who also happens to be a landlady, often is assumed to be a lady cosplaying as a high school student (mostly because the tenants are generally otakus themselves, so it's not a big leap). Amusingly, her mother actually works at a Cosplay Café and was mistaken for Taeko's friend when she turned up in her work uniform. The combination of the two tropes lead to Taeko looking older than her mother.
Technically the case for all the NPCs in Overlord (2012); while their physical ages vary widely, they were all created as player-created NPCs in an MMO that had a twelve year run. Since it would have taken a few years before any of their creators were able to make them all of them actually have single figure ages.
Isabella from Paradise Kiss is high school age, but dressing like a middle-aged Victorian lady makes her look remarkably older. Her very mature and composed attitude only add to it, as do her knobbly, slightly manly hands.
In Planetes, a minor character is 12-years-old, but since she grew up on the Moon with it's lower gravity, her growth rate was accelerated and her size makes her look like she's in her early twenties. This causes the twenty-something main character to be really uncomfortable when he discovers her true age... especially since it appeared he'd been developing something of a crush on her.
Team Rocket (or more specifically Jessie and James) are supposed to be 15, despite looking and sounding significantly older than everyone else. Subverted, as this is implied to be them lying about their age, as other material suggests Jessie is 25. While some semi-official English sources back in the day placed them around 17, the original is explicit about them approaching 25. Jessie's rage button about being called an old hag/oban is because she nearly is one, her mother Miyamoto laments it in her recordings (snippets of Miyamoto's ramblings while lost in the Andes mountains at the start of each chapter, talking about her daughter she couldn't watch grow up, provide us with clues as to when each part of Mewtwo's origin story takes place). This is also the reason for her obsession with getting married and settling down as soon as possible. By Diamond & Pearl, James also looks visibly pained when a little boy calls him ojisan (implying he's an old man).
A lot of the 10-year-old characters, such as Gary and Misty, look more like they're in their early teens. Some unofficial sources even listed Misty's age as 13, probably since she's taller than Ash. Even Ash looks a bit older than ten in the earlier seasons.
Miki Aono/Cure Berry from Fresh Pretty Cure!. She's a gorgeous aspiring model and quite tall, in fact, the tallest of the Fresh Cures and the second tallest overall Cure (only beaten out by Yuri Tsukikage/Cure Moonlight from HeartCatch Pretty Cure!, who's the oldest of all active Cures) and is only 14.
Aguri Madoka/Cure Ace and Regina from Doki Doki! PreCure. Aguri is 9-years-old, ages up to about 14 as Cure Ace and Regina's about the same age as the Cure Ace form. They're only less than a year old. It's a long story.
Asumi Fuurin/Cure Earth, a spirit of the earth, is born in the middle of the show to protect Latte, and despite being chronologically a newborn, she takes on the appearance of a 20 year old woman.
Occurs with the all young girls in Junko Mizuno's Pure Trance manga; they appear to be about three when they're born, and one quickly ages about 16 years in a matter of months due to her ability to shed her skin like a snake.
Pretty much all the characters of Revolutionary Girl Utena fall into this, due to their willowy Noodle People designs, refined uniforms, and the kind of things they get into. Utena and Anthy are fourteen, while Nanami and Miki are thirteen, but they all look like they're at least sixteen or seventeen, the ages of Juri and Saionji.
Aria from Rising × Rydeen looks like she's in her mid-twenties and compared to the rest of the mostly teenage cast she's significantly taller, bustier and more composed despite being eighteen, only three to four years older than most of them. Takara is shocked when she reveals her true age.
In Sailor Moon, when ChibiUsa and Hotaru are possessed, they take the forms of adult women, though they both are children younger than any of the other characters. Averted in Chibiusa's case as, at least in the manga; she is really 900-years-old.
In Sankarea, Darin looks to be somewhere in her mid-20s to early 30s, but eventually lets slip that she's actually only 14. The other characters are so dumbfounded by this that they focus more on the fact that they're actually older than her than anything important she's telling them. Her older appearance was likely intentional on her part, but even after she relaxes her "mature" look somewhat, it's still very rare for her to actually look 14.
Megumi of Servant × Service may look like a senior staff, but that's mainly out of the effect of her stoic demeanour. She's actually 20, in the same age of the youngest newcomer in her office.
Yagi Yuria in Shibatora works at a maid cafe, passing as over eighteen, but is really only 12-years-old. The fact that her mental maturity is normal for her real age, not her appearance, results in her being exploited by a number of other characters.
Yukata and Tomo from Shonen Note: Boy Soprano are both just beginning middle school at the start of the manga, however Tomo looks much more adult. He's a very tall kid who towers over even many, if not most, adult characters and looks like a lanky teenager. His parents expect him to act like an adult which upsets him because, despite his appearance, he's emotionally and physically still just a kid.
Primula from SHUFFLE! appears to be around eleven or twelve years of age. She's actually younger, since she's the most recent test subject of the Yggdrasil Project.
In Slam Dunk, Shinichi Maki, the captain of Kainan team, looks like he was over 35 but he is only 17. After learning it, Hanamichi immediately nicknames him "Middle-aged Man" and never calls him by his real name. Maki retaliates by pointing out that Akagi, Shohoku's captain, looks even older. And later on in the series, Uozumi (who's the same age as Akagi), is mistaken for Akagi's father.
Zelgadis the chimera of Slayers is 20 at the start of the Light Novel series, and his appearance appropriately matches his age. In the anime though, his age is bumped down to sixteen (a Word of God statement in a film book), making him fall under this trope. It doesn't help that his voice is noticeably deep, especially in the English version. More often than not, Gourry (who's older and taller than Zelgadiss is; in the anime, he's the only protagonist who starts out in his twenties) is referred to as a boy.
Bill Watkins from Spy X Family is only six years old, but he's also very tall and muscular, and the anime gives him the deep voice of Hiroki Yasumoto. It's stated that he developed very early, and it's also likely to be genetic since the anime shows that his father is similarly huge (with Bill only coming up to his father's waist). This is lampshaded by Becky, who disbelievingly says there's no way he can be the same age as her and the other students in their grade.
Umehachi, male protagonist of the manga Tende Freeze, is 17, but looks like he should belong in junior high. (Admittedly, he regularly acts that age, too.) This is repeatedly lampshaded with people who get it wrong; his brother is in junior high but looks far more grownup than his brother (and, again, acts the part too...); when they go to the movies, they buy each other's tickets to avoid lengthy explanations.
Yoko in Tengen Toppa Gurren Lagann is actually 14, the same age as Simon. However, since humans had been living underground for generations, without a sun or anything, they probably couldn't tell time as accurately, so who knows. Although, supplementary material, such as the official anime guide, states that she is actually 18.
Tentomushi no Uta: The four oldest Isshuu siblings, Tsukimi, Kaji, Mizuo and Mokusuke, are respectively 11, 10, 9 and 8 years old, but look as if they are in their mid-teens at the youngest.
That Time I Got Reincarnated as a Slime: Rimuru is both this and Older Than They Look: in his human form, he looks about 16/17 at the very oldest, but at the end of the series he is only about 3-years-old. His mental age is around 40, having died as a human at 37 at the start of the series, and being reincarnated with all of his memories.
In Touch (1981), Sohei Harada is a high-schooler, but he looks ten years older and towers over all of his classmates.
The main character Vash starts out in this form, seeing as he's really a plant-like alien who matures into a young child far more rapidly than a human would; when the series opens, however, he's Older Than They Look, seeing as he's existed since before the incident that initially colonized the planet.
Wolfwood in the manga does have a lampshaded case; The experimental treatments his Evil Mentor used to give him superhuman capabilities and Healing Factor also caused him to age faster; while he looks in his mid-to-late 20s, he's probably sixteen or so when we meet him. His former guardian at the orphanage doesn't recognize him until Livio's about to kill him.
The movie Badlands Rumble sees Amelia McFly, a bounty hunter, who could pass for someone in her 20s. Her real age is actually 19 as she was born after an earlier meeting with Vash and her father, Gasback, that took place 20 years ago.
Ame from Wolf Children by the time he decides to leave civilization and live out his life in the wild as a wolf he looks and sounds like he's in his mid-teens, but his mother Hana states that he's 10-years-old.
In Yona of the Dawn, it's astonishingly easy to forget that Hak is actually seven years younger than 25-year-old Jaeha, given how well they get along and how much their maturity level seems to match up. Jaeha too seems to deem him as the second adult in the manga's main cast, as he's the only character Jaeha doesn't use the "-kun" honorific to address him with — and that includes Kija, who's a good 2 years older than Hak is. 15-year-old Yun Lampshades it at one point, admitting that he honestly forgot Hak was younger than Kija. Kija gleefully asks Hak to address him as "older brother" in response.
Yu-Gi-Oh! GX has Professor Banner, who looks like he's in his mid-20s, but he's actually 18. It's because that at 18, he contracted a terminal disease while doing alchemy research, so he made a second body to continue research and stop the funder of his research, Kagemaru.
Jean-Jacques Leroy is 19, but his height and toned build make him look older than main character Yuri Katsuki, who despite being 23 could still pass as a teenager.
Emil Nekola is 18, but his facial hair makes him look older.
Otabek Altin is 18, but what makes him look older than that is his stern-looking and angular face.
YuYu Hakusho has an early joke about this — a creepy one-shot youth gangster who kidnaps Keiko in the manga, who has an oversized head with overdeveloped bone structure and a load of stubble. In an early panel where he's perving on Keiko his face is labelled, '14-years-old.' I.e., in his last year of middle school.
like he's in his late 20s to early 30s, but at the time of the Golden Age his actual age was 19. For contrast Corkus is a year older than Pippin despite looking younger,
