A common Japanese media character type, the female high school teacher who is fairly young, attractive, even cute, and on friendly terms with her students.
On the other hand, she is still unmarried, and very conscious about it, as well as about the lack of respect she gets. She is usually extremely childish, such that even her own students appear more mature than her.
If the story's emphasis is on the female students, she will act like one of the girls, a teenager in spirit. In Harem Series with a male protagonists, she is more likely to be a bit Hot for Student, as a comical side-character of the harem. A common character flaw Played for Laughs is being a Hard-Drinking Party Girl.
Their frequent complaints about being unable to settle down in a proper relationship, are probably based on the traditional Japanese culture's conflicting expectations, that a married woman shouldn't work, and a woman over 25 should be married, and for the intended audience of Anime, schoolteachers provided the first, childhood exposure to women with this dilemma, enforcing the stereotype that teachers are the sort of women who can never get married.
The trope's name is a combination of two honorifics, "-sensei" is used for teachers, like "Miss", and "-chan" is an informal affectionate diminutive. While the combined usage is grammatically correct, and it reflects the characters in spirit, it's unlikely that anyone would use it for a Real Life teacher either in this form, or as "-chan-sensei", since it would be about as conflicting and disrespectful as "Miss-baby", or "Teacher chick" in English.
On the other end, they tend to referred to on First-Name Basis by their students, which is incredibly rare in real life. "-sensei", like its western equivalents, is normally associated to the last name, but these characters may as well not have one.
- Minamo "Nyamo" Kurosawa and Yukari Tanizaki from Azumanga Daioh are probably the Trope Codifiers, especially the latter. Yukari actually still lives with her parents and doesn't have a driver's license; she might as well still be 15!
- Nyamo is more mature and tries to keep Yukari in line. But don't remind her that she's still unmarried.
- Tomita "Tonchan/Tom-Tom" Mari, from Air Gear, is so young that one of her colleagues, who's in his mid 40s at the most, was her teacher when she previously attended the school. And she's incredibly childish and naive. By the way, she's definitely of the Hot for Student kind.
- Sawa-chan from K-On!, who actually is addressed on occasion as "Sawachan-sensei".
- Kuroi-sensei from Lucky Star. Like some of her students, she spends a lot of her free time on MMORPGs. Unlike them, she's at least mature enough to not sacrifice sleep for gaming time. This is lampshaded in the manga.
- Koigakubo-sensei from Toradora!.
- Played with by Hinako Ninomiya from Ranma ½. She's got a weird condition (caused by Happosai doing something odd to her when she was a sickly child to help alleviate her illness) where she oscillates between a sweet-cute child form and a voluptuous adult form depending on how much battle aura/ki she's drained from her students recently. The interesting part is that she undergoes a personality change with the size change—she's mentally a child when in child form, and far more sophisticated as an adult.
- Yokoshima-sensei from Seitokai Yakuindomo, also from the perverted Hot for Student kind.
- Yukari in Nogizaka Haruka no Himitsu. Acts very immature, constantly hits on the male students - particularly the main character, who's the younger brother of her best friend and drinking-buddy - and they all completely ignore her.
- Taiga Fujimura from Fate/stay night.
- Mika-sensei from Doki Doki School Hours (whose original manga version predated Azumanga Daioh by a few years) is probably one of the more extreme examples: Despite being 27, she looks and (for all intents and purposes) acts like a twelve-year-old, and as such her students have a hard time taking her seriously.
- There is Hibiki-chan from I My Me! Strawberry Eggs, of course she is a Wholesome Crossdresser.
- KoMoe-sensei from To Aru Majutsu no Index definitely seems like this, since she looks like a ten-year old girl who sleeps in cute pajamas, is friendly with her students, and is implied to be a bit hot for her 'Kamijou-chan'. However, she also smokes heavily, drinks beer heavily, is implied to be at least in her 30s (and possibly much older), and most importantly of all, is an actually smart and competent teacher who acts as a mentor for Touma.
- Negi Springfield from Mahou Sensei Negima would definitely be a gender-inverted
versionexaggeration of this, being a ten-year-old male teaching a class of 31 fourteen-year-old girls. In some areas the trope is inverted entirely as he's far more mature than them, while in others he acts his age (he has the work ethic and emotional maturity of an adult, but still avoids taking baths and is easily flustered).
- Becky from Pani Poni Dash! is another exaggeration / parody, she's eleven years old, has graduated from MIT, and teaches high school.
- Vera Collins from Heroman.
- Naru-chan from Girl Friends. Actually referred to AS "Naru-chan-sensei," though not to her face.
- The nameless Teacher from Eiken.
- Uzuki Shitenno of Happy Lesson.
- Yoshinoya-sensei from Hidamari Sketch.
- Kyouko "Boin-sensei" Houin from Kodomo no Jikan fits most of the characteristics. She's definitely the most popular teacher (especially among the boys), but the students don't respect her much.
- Haruna Sakurada from both Sailor Moon and The Cherry Project is a good and early example. The English dub turned her into another cranky teacher, so this aspect of her personality was gone.
- Usami-sensei in GA Geijutsuka Art Design Class, like, more afraid of blood donations than her students. This is kind of justified in-universe as she's just in the second year of teaching.
- Subverted in Code Breaker. The homeroom teacher is a ditzy Hot Teacher who seems to be one of these. Then it's revealed that she's actually The Handler, and the ditziness is an act.
- In Sket Dance, there is a cute, cheerful and ditzy teacher, formerly a children TV show host, who insists that the students call her "oneesan".
- The teacher from FLCL is trying to be this... not especially doing that well, though.
- Kazuko Saotome in Puella Magi Madoka Magica. Her Establishing Character Moment is complaining about her love life to her class before introducing the New Transfer Student... Too bad the poor "girl" lives in a Crap Saccharine World. Which costs her her life in the Alternate Universe Oriko Magica, as she's Eaten Alive by a witch's minion.
- The alternate universe scenario in the final episode of Neon Genesis Evangelion put Misato into this role, rather appropriately.
- Sakurai-sensei from Nichijou.
- Marie Mjolnir from Soul Eater fits the bill in most respects. She's such a Christmas Cake that she tries to marry a toilet! She does have a dose of Crouching Moron, Hidden Badass, though.
- Ritsuko Takahashi from Hell Teacher Nube.
- Hitomi Shimonome from Loveless. It's not pretty, though.
- Kyouko Ono from Kenichi: The Mightiest Disciple. She's very young and rather inexperienced, looks very cute when she cries, and she really doesn't know how to handle her rowdier students, but she's very caring and is able to help Boris come out of his shell.
- Yukiji Katsura from Hayate the Combat Butler.
- Mayuko Shiraki in Fruits Basket; teacher of the students in Tohru's class. After some of her female students address her as Mayu-chan-sensei, she demands(jokingly) that they call her Mayuko-daisensei-sama.
- Ayane "Ayanecchi" Tezuka from Rouge Noir is the very rare protagonist example.
- Yomiko Readman of Read or Die occasionally becomes this, given her cover identity as a substitute schoolteacher. This doesn't turn up in the OVAs or anime, though she had been one to Nenene.
- Machiko-sensei from Rinne no Lagrange.
- Kisaragi-sensei of Umi no Misaki, another teacher who looks and acts like a twelve year-old and constantly hits on the main character. She is rather brighter than she acts.
- Tsubame-sensei from Ai Kora mostly fills this trope. Young, unmarried, and hangs out with the girls in the dorm as well as part of the main characters harem. Can be considered partially subverted because she does not want to get married, in fact her character development has her letting go of her deceased boyfriend and admitting interest in a new man.
- Mitsuka-sensei from DearS wants to be this. However, while she has the "young, attractive and immature" part down, she completely overdoes the Hot for Student part and the whole thing just leaves her students disgusted.
- In Persona 4, Noriko Kashiwagi seems to think she's this. She isn't. And her students think it's pathetic
- Quistis Trepe from Final Fantasy VIII. Justified by the fact that she's the same age as her students, but managed to graduate several years early, and was insane enough to get a job teaching her former classmates soon after.
- Misato in Snow Sakura.
- Played with in Muv-Luv. Jinguuji's students in the Extra part all call her Marimo-chan, and the usual Christmas Cake jokes get played. In the Unlimited alternate universe, she is not amused by the protagonist addressing her as Marimo-chan and demands to be addressed properly.
- And then there's Alternative, which not only plays with this trope but uses it as part of a horribly soul-crushing plot twist. Twice.
- Miss Grotke from Recess has some shades of this trope. She's pretty much loved by all her students (and takes a Cool Big Sis role to Spinelli), young and unmarried (not a Christmas Cake really, but it's hinted that she's in her early 30s), and is arguably, pretty Moe.
- Sun Park from American Dragon: Jake Long is on a First-Name Basis with her high school students, is young and pretty, and is a gentle mentor to Haley.
- When she's not portrayed as an Apathetic Teacher, Mrs. Krabappel comes across like this, particularly when outside of the classroom (though occasionally in it.)