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Note: Due to the episodic nature of the series, spoilers are unnecessary for the following tropes. Though the last few Manga chapters contain some serious spoilers so best not to read spoilers until you've read the Manga to the end.
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The Itoshiki Family
The Itoshiki family is a powerful clan dominating over their native Kuraizawa, Shinshuu Prefecture (a No Communities Were Harmed version of Karuizawa, Nagano Prefecture), whose name (糸色) can be compressed to read as 絶 — "zetsu" ("beyond") — which often serves to undo the specific meaning of each member's names... thus one can re-interpret "Itoshiki Household" (糸色家) as 絶家 — "zekke" ("extinct family").
Better to Die Than Be Killed: Nonfatal comedic version. Although he often attempts to commit suicide very often, the times he actually gets closer to death is when someone else gets involved, mainly Kafuka, to stop his attempt and thus the second catchphrase makes sense with this in mind.
Clueless Chick Magnet: All he does is rant about whatever is currently bothering him, somehow attracting the attention of almost all of his female students in the process. Even after he's earned their attention, he almost never seems to realize their feelings for him.
Christmas Cake: A male example. His family is constantly trying to marry him off before his 25th birthday.
Jerk with a Heart of Gold: A snarky, apathetic teacher he may be, who is also prone to breakdowns and occasionally dying (and coming back to life), but nevertheless he shows genuine concern for his students — well, some of them, anyways.
Jerk With A Heart Of Jerk: On the other hand, he couldn't care less about his "secondary students", which is played for laughs.
Large Ham: A family trait, though he probably tops his siblings.
Limited Wardrobe: Always wears a kimono and hakama, otherwise anything retro and Japanese. Sometimes subverted, however — as his students found out, he wears casual western clothing in his native Kuraizawa.
Motive Rant: Ruthlessly parodied, as he rants every episode about his latest reason to commit suicide.
Mr. Fanservice: A parody. He's a Reluctant Fanservice Guy, and apparently, every character attracted to him (thereareafew) sees him as a different stereotype or archetype, mostly because the class's ideas of what is generally considered attractive are cobbled together from shoujo anime and badly written manga. It is occasionally played straight, though.
Nigh-Invulnerability: Survived every threat on his life, self-inflicted or otherwise — he was hanged, stabbed, bludgeoned, exposed to carbon-monoxide poisoning, got ran over by a runaway streetcar, attempted to drown himself (or drink himself to death) in a bowl of Dom Perignon, overdosed on OTC medications, and even had his name written on the Death Note. Even when he does die, it doesn't ever stick, much to his consternation. Incidentally, popping out of his coffin at his own funeral to tell everybody to stop blaming themselves for his death inadvertently spared him (and Matoi) the inconvenience of having to survive cremation.
Oblivious to Love: Despite all of his female students having massive crushes on him, he's barely aware of their feelings at all. It seems to be more of a case of him just not caring rather than actually not understanding it.
Only Sane Man: At the end of the day, and in stark contrast to most of his students, Nozomu is actually a sane, rational man whose pessimistic streak stems mostly from his high school days as an accidental member of the "Negative Club".
Youngest of the five Itoshiki siblings (and the only female), an ikebana master with a major complex towards the Alternate Character Reading of her own name. She eventually becomes a student in 2-He, under the tutelage of her immediate older brother Nozomu.
Berserk Button: Spell out "zetsurin" and she will scream for a katana in no time.
The Maiden Name Debate: She badly wants to get married in order to lose her maiden surname and consequentially her sexually-suggestive nickname. Unfortunately there's a Japanese custom that if the bride is of a wealthy clan (the Itoshiki family is one such clan) the groom can opt to adopt his wife's surname instead, and one of her suitors, Nozomu's "old friend" Ikkyu, is all too happy to be part of the centuries-old clan.
Nozomu: You'd better give up, Rin. Father will find this far too entertaining. He won't wanna put a stop to it.
Meaningful Name/Punny Name: Her name, written horizontally and compressed, can be read as 絶倫 — "zetsurin" ("peerless"), which at first glance refers to her expertise at many skills (which involves her getting random odd jobs out of nowhere), but is also (much to her ire) a slang for sexual prowess.
The Ojou: She fits both the traditional (style of dress, an ikebana master) and snobby (enters Nozomu's school just to feel what it's like being a commoner, buys off all surrounding property and evicting their residents) variants.
Screw the Rules, I Have Money!: One segment has her buying the entire neighborhood she lives in, so she can move around without fear of Chiri checking on her every hour.
Free-Range Children: Is pretty much this thanks to Parental Abandonment. There's references in the manga to the girls in the class taking turns raising him, but other than that, he's pretty much on his own, as Nozomu isn't really parent material.
Innocent Prodigy: Comes across as more mature and down-to-earth than his uncle, but can also act in a way fitting his age. There's also some situations that might be either this or Ping Pong Na´vetÚ, like having a crush on a net idol and commenting on her breasts, while also thinking that storks deliver babies.
Meaningful Name/Punny Name: His name, written horizontally and compressed, can be read as 絶交 — "zekkou" ("breach in a relationship"), hinting to his broken family and having to stay with his youngest uncle.
Mr. Exposition: Share this status with Chie-sensei in several last chapters, explaining the circumstance of Kafuka's Hive Mind in class 2-He and Nozomu's reason for persisting teaching the misfits. Doubles as Secret Keeper.
The Ghost: He's mentioned several times, and actually left a note in one chapter, which read "I searched everywhere, and couldn't find you guys." He finally appears and meets up with his family in the last volume.
The Itoshiki siblings' father and a member of the Diet, the Japanese Congress.
Genre Savvy: Implied when Nozomu tried to talk Rin out of her desperate attempts to get married away from the family and from her maiden name with an embarrassing Alternate Character Reading, saying their father won't stop having fun with making Punny Names.
Nozomu's high school homeroom class. The "He" (へ in Hiragana) signifies that it is the sixth second-year section based on the iroha order (in modern nomenclatures this would be called Class 2-6 or 2-F). The class is said to have 32 students, though so far only 23 have been named.All students in this folder are in Nozomu's class unless otherwise noted. Nozomu's younger sister Rin is also a student in this class.
The creepily optimistic main female lead, who often gives an extremely implausible positive side to anything Nozomu is currently ranting on.
A God Am I: Subtle, but it exists. Her goal in life is to be a God (her other goal is to be an alien). There's also an instance where she practically psychologically tortures and brainwashesnote namely by entirely isolates them in jail and becomes a messianic figure who release them Nozomu, Nami (who turns out has a quite large ego herself), and several others into thinking that she's a Goddess. In the end of the manga, she's succeed. In a way...
Big Bad/ Big Good: Depends on your interpretation of her actions. On the one hand, she saved the entire main cast from death and continues to prevent them from committing suicide while at the same time brain washing them into a hive mind.
Body Surf: Her spirit has been alternately possessing different girls from the class since the beginning of the series. Only the recipients of Kafuka's organs or blood can see her; the rest will only see her host acting out of character.
"How could (subject of Nozomu's rant) be possible? It's just (highly implausible theory)!"
Cloudcuckoolander: Believes that, one day, the Pororocoaians will descent upon the Earth, among many other things.
The Cloudcuckoolander Was Right: When she and Itoshiki are trying to lure Komori Kiri out of her home, Kafuka remarks that she must be a ghost that lives in buildings and brings it and its inhabitants good luck. When she is eventually coaxed out of the house, it's later revealed that it collapsed and killed her father in the process. Later, the very same thing happened to the school after Komori left it.
Corrupt the Cutie: As the series went on, her psychotic tendencies and violent outbursts became more frequent and extreme.
Cute and Psycho: While she's fairly stable right now, her classmates and friends fear the day she snaps and murders the entire class, which they predict isn't too long away.
Dead All Along: In the second to last chapter it's revealed that she died long ago and donated her organs which made their way to all the other girls in the class. This means that she was able to possess each girl and every time we saw her it was just one of the other girls and the other girls saw her as Kafuka. In the episode that introduces Meru it was Abiru hence why she had a bandage on her arm. Yes, it's been foreshadowed from the beginning—including the anime OPs.
Hilariously Abusive Childhood: Her schizophrenic father once tried to commit suicide several times before and/or kill her, and her mother was once possessed by an evil spirit. Whom she had to kill by beating her with a cross. Among other horrible things, she has a fiance - and it's implied it was a forced marriage arranged by her one dead parent and other schizofrenic parent.
It's implied that her father took out a huge insurance on her, and then threw her infront of a car.
Insane Troll Logic: All the time. It's both pants-wettingly disturbing and freakin adorable. Like how if she fed herself to a lion, she'd become God, even though Buddhism has no God, and Shintoism has multiple Gods, meaning there is no "God". Or how one day, when all is beautiful and peaceful on a summer's day, the Pororocoians shall descent upon the Earth.
Ironic Nickname: Played straight and subverted. Her pen name, "Kafuka Fuura", comes from Franz Kafka, the author of Metamorphosis, her favorite story. One morning, when Kafuka Fuura woke up, she had become Kobushi Abiru, Kitsu Chiri, Matoi Tsunetsuki...
Karma Houdini: Her father, who took out a life insurance on her and threw her in front of a car. He is no where to be found, and is implied to have fled the country.
Kill the Cutie: She's actually been dead for a very long time. The problem is that nobody's noticed.
Meaningful Rename: There's a reason for Kafuka's pen name. The girls who received her organs, and thus were possessed by her because of this, only knew that their donor was "a teen from the Tokyo area". This is why their collective consciousness, being unable to accept the impersonality of this, gave her a name after the author of Kafuka's favorite story: The Metamorphosis.
One morning, when Kafuka Fuura woke up, she had become...
Miko: Is one when volunteering at her local Shintoist shrine. She herself is a syncretic Buddhist/Shintoist, like many Japanese people.
The Nicknamer: Once called Nozomu "Momoiro Kakaricho" ("Pink Superintendent"), after she caught him trying to hang himself on a sakura tree.
Nightmare Fuel Station Attendant: Once drew a very detailed picture of a very detailed car accident, often says highly disturbing things - usually accidentally - that frightens her classmates.
In several scenes, it becomes glaringly apparent that all of her classmates - including the musclebound illegal immigrant, Knife NutControl Freak and The Big Girl - are all incredibly afraid of her, and they all fear the day she loses her mind and kills each and every single on of them.
Nice Guy: Despite the madness that happens around her, a world that has lost its mind, and her one true love offing himself every other weekend, she is still optimistic, and is good at gathering people for a cause. After she died and being to possess her classmates, she activated some sort of genetic code in her organ she left, stopping them from killing themselves. As Chie puts it, "She's like a mother to the entire class."
Shipper on Deck: Kafuka actually ships virtually the entire female half of the class (or at least the 12 main girls) with Nozomu, even though she also wants him too. Makes sense considering all of them are actually her host bodies as revealed in the final three chapters.
Someone To Remember Her By: A female example. While her friends eventually forget that she ever existed, her numerous children who look exactly like her, and are just as optimistic and friendly.
Stepford Smiler: This gets bigger and bigger every episode, to the point where it seems like Kafuka is always on the verge of a complete and utter breakdown. She is. By the end, she's basically a walking smile hiding an all-consuming void of agony, and it's hilarious.
In one incident, Kafuka challenged her and other girls to a "Schrodinger's Wife" dilemma, to see who Nozomu would pick. Chiri tries to force herself onto Nozomu, much to the guy's distress. Later that day, she starts having paranoid thoughts that people may be badmouthing her behind her back, and decides to turn Clas 2-He into a "class in potentia".
Meaningful Name/Punny Name: Four alternate readings, to be exact. Her full name (in Japanese order) can be read as きっちり — "kicchiri" ("precise"), referring to her Super OCD. Her given name can be compressed to form the first kanji of 埋める — "umeru" ("to bury"), which explains her spade, or used as the first two kanji for 千里眼 — "senrigan" ("clairvoyance"), explaining her Third Eye. Finally, her given name can be an onomatopeia, "chirichiri" ("frizzy"), as her hair is actually frizzy, and she has to frequently iron it out to give it a perfectly straight look.
A student who's frequently wrapped in bandages. Contrary to in-series popular belief, she is not a victim of domestic violence; rather, her injuries are caused by irate animals victimized by her tail fetish.
Cut Himself Shaving: Subverted — she's frequently thought to be a victim of domestic violence; in reality, her injuries are caused by animals whose tails she pulls.
Dark and Troubled Past: She attempts to kill herself by launching herself off of a balcony before the series starts.
Deadpan Snarker: Very much so. She always has a bored, nondescript experssion on her face, and although she drops in and out of focus - as is expected with a cast this large, even if she usually is in focus - she has many a good snark. Her first - and establishing - is when Kotonon says she's never been called fat before in her life, Abiru's only response is, "Really, never?".
Duality Motif: Her green left eye (a result of a corneal transplant), which is frequently covered by an eye patch; the other is brown. In one chapter in Volume 8, she indicates that it was transplanted from a victim of a car accident, and even claims she can see the last thing the donor saw — the license plate of the killer car. The eye happens to be from one An Akagi who is better known as Fuura Kafuka. She also sees the other girls as Kafuka through her transplanted eye, foreshadowing the reveal that Kafuka is possessing the girls in Nozomu's class.
Emotionless Girl: Except whenever talking about animal tails or alone with Nozomu.
Fetish: Animal tails. She even has a part-time job at the zoo just to indulge her obsession, and frequently gets injured by irate animals whose tails she loves to pull. She even has walls full of mounted animal tails.
She'll also occasionally use her bandages in bondage-y scenarios, often with Nozomu on the receiving end.
A hikikomori accidentally scared out of her home by Nozomu and Kafuka; she has since become a resident at school and eventually a caretaker figure for Nozomu and Majiru.
Bi the Way: Has a rather suggestive relationship with her teacher, Chie. She raises no objections, even if the focus of her affections are then moved to Majiru, it's heavily implied that her and Chie's exploits are still happening.
Hikikomori: It seems her avertion to the outside world is a conscious choice; when she got cornered by Nozomu and Kafuka to attend school and when she sleepwalks, she can go outside. Though she wants to go to many places, including the sea and the meadow, she can't never go outside as long as she has a say for that.
I Take Offense to That Last One: Call her a shut-in, call her a house fairy, and she only notes it for a moment before dismisses it. But call her a NEET, and she will protest. After all, she has a job as a freelance computer programmer; never mistake a shut-in to a NEET just because she never goes out.
Deadpan Snarker: Not as much as Abiru, but she has a quite dry wit even toward Nozomu, as shown when he brought a lot of TV that were half-assedly made with calculation that quantity is better than quality.
Matoi: No matter how much you made it, shitty TVs are still shitty.
The only normal girl. Her original "gimmick" was her truancy, but then she showed up to school and lost her only trait that could be considered unique. Ever since she has been playing the Straight Man, whether she likes it or not.
The Generic Girl: Much to her distress. So generic that in Bangaichi even real-life movie subtitle writer Todana Tsuko, (in)famous for her absurdly liberal translations of foreign films, had nothing special at all to say about Nami.
Hollywood Pudgy: In-universe, as the result of Characterization Marches On. A bit glutton (especially if it's ramen) and having a complex over her weight with those diet plans and pills she often mention. Of course, she's one of the show's main girls, she ends up as skinny as the other girls. This being Zetsubou Sensei, this trait is properly mocked and lampshaded.
Not So Above It All: Is shown to cut herself, has many weight issues, and much like her teacher, repeatedly tries to off herself to gain attention. She's definetely a mentally disturbed person, it just so happens she's in a class of even more mentally disturbed people.
Obsessed with Food: Her later characterisation renders everything she says and does into a joke about how she's fat, and all of it has to do with fatty foods, like donuts, cakes, and sweat bread.
Straight Man: According to Kafuka, she is "more normal than most people". Of course, this is subverted and Played for Laughs during her proper introduction at the first episode of Zoku, where she claimed to have various problems no normal person would have just to garner attention and sympathy, only to be outdone by her classmates, so she threatens suicide. Of course that is the moment Itoshiki makes his appearance by attempting to hang himself from the school roof. Only Nami reacts to it though.
The resident doujin artist and yaoi fangirl with a taste for slash pairings (usually involving famous anime characters, her own teacher and some of her male classmates, but especially "Pine x Napple"), as well as a hidden athletic talent.
The Ace: Not to the extend of Chiri, but still she's a star student and athletic genius without peer. Only thing that holds her back is her love for her doujins.
Badass Bookworm: Sort of — she's a manga-loving nerd with incredible athletic prowess.
Boobs of Steel: Harumi appears to be amongst the bustiest (though not the very most) in a class full of some very curvy women (the fact that the animation seems to regularly focus on her breasts helps quite a bit), and is also phenomenally strong.
Childhood Friends: With Chiri. She knows many things about Chiri's past (such as the circumstance of her sister's extreme hygienic problem) while Chiri trusts her to do many things perfectly when Chiri herself can't do it, which she does just that.
Power Limiter: Her glasses are said to be one. She has incredible athletic talent, but doesn't want to use it for fear of being scouted to a sports club and thus chip away at her time drawing her yaoi doujins. Said glasses are also quite heavy.
A brown-skinned illegal immigrant who bought her name and identity from a male bum.
Ambiguously Brown: Generally implied to be a Filipina (a Hispanicized real name, her home nation's close proximity to Japan and its poverty-ridden, war-torn history), although she claims her previous school was "Mesopotamia Academy".
Barefoot Poverty: Is portrayed like this with socks and shoes. Even after the others in the class try and get her into a Instant Cosplay Surprise or other normal outfits actually wearing socks and/or shoes, it gives her vertigo because she has never worn them before.
Mama Bear: Evokes this instinct from anyone who sees her, including lawsuit-happy Kaere.
Meaningful Name/Punny Name: "Taro Sekiutsu" ("Maria" is her given name), a name she bought from a guy willing to sell everything connected to him, can be read as 籍売ったろう — "seki-uttaro" ("I'll sell my name").
Naked People Are Funny: As the manga went on, her skirt became less magic, and she developed a tendency to flash unsuspecting, poor individuals. Her nudity tend to get played for humour.
She finally manages to mutter out a "Thank you," in the last chapters of the manga, though Kafuka is the only one to hear her.
GIFT: An interesting case. She's a seemingly plain old Shrinking Violet unable to communicate verbally. However, with the power of texting she can (and does) unleash torrents of verbal abuse on the undeserving people around her. The odd part is that she does this while only standing a few feet away from them and personally giving them her e-mail address, taking away the anonymity aspect that usually is the reason GIFT exists.
Meaningful Name/Punny Name: Her given name is a loan word for "mail" ("メール"), and her surname means "soundless". In addition, her email address "hazukashigariyasan" means 恥ずかしがり屋さん — "full of shyness".
Lolicon: A ruthless parody. The only people who fall for the little brat are pedophiles, weirdos, and pathetic losers who can't attract real women. In fact, she gets kidnapped by said pedophiles, weirdos and losers. A lot.
A foreign transfer student recently returning to Japan as a student of Class 2-He with a personality split between Kaere, a lawsuit-happy Jerkass and the in-series Ur Example of the "obnoxious foreigner" stereotype, and Kaede, a Shrinking Violet.
Attention Whore: It's pretty clear that she seeks attention by flaunting herself and then loudly threatening to sue onlookers.
But Not Too Foreign/Fauxreigner: She's half-Caucasian (of indeterminate nationality). A map of Britain appears when Nozomu is discussing her return, but she comes off like a JerkassAmerican... until she starts bringing up animal sacrifices and other pleasantries. She probably just represents the outside world that is blonde and not Japan. Eventually, it's revealed that the "country" she returned from is the island that Nozomu and the others move to at the end of the manga.
Also, this little exchange between her and Nozomu.
Kaere: The (custom in question) in this country [i.e., Japan] is/are weird! In the country where I came from we (perform an extremely bizarre custom). Nozomu: I gotta ask... which country did you come from, anyway?
Chuck Cunningham Syndrome: For hundreds of chapters at a time, she can get no dialougue. After Chapter 170, when Itoshiki became less constant, Kafuka became more constant, and the art gradually began to shift to its old style, she still appears once every 30 or so chapters. After a certain chapter early in the manga's run, she didn't even appear in the background to moon unlucky pedestrians. And this is just Kaere in general—references to Kaede turn up only a handful of times out of those few appearances.
The only married student in Nozomu's class who frequently complains in class about her unhappy marriage.
Cool Big Sis: Mature, motherly, and always has hugs for everyone. Other than her extremely morbid realistic view of the world and multiple part-time jobs that she often brings to the class, she's one of the sanest characters of the show. Marriage does have its own quirk, in a way.
Out of Focus: Played with. While he is Nozomu's most recurring male student, he is often ignored whenever he attempts to tell his personal experiences and/or examples related to Nozomu's rant of the moment, meant to be even worse than previous examples presented.
(Random character): Did you hear someone?
Power Perversion Potential: Despite frequently complaining about his situation, however, Usui has, every now and then, used his invisibility for... less than worthy causes.
Prematurely Bald: To add insult to injury, he only becomes visible whenever his balding head gets exposed.
*Kagero looks at an overembellished avatar Kiri made of him that is still balding* Kagero: Um, isn't there a part that could use some more embellishment? Kiri: It's already over-embellished as it is.
A Day In The Lime Light: After several changes happened in the manga (especially around chapter 170) he started to appear much more, coincidentally ramping up the Ho Yay between him and Itoshiki. He even started appearing more than some of the girls. Played for laughs, of course, until the ending...
Dark and Troubled Past: An illness forced him to get a blood transfusion, getting him kicked out by his incredibly religious family. He then tried to commit suicide, but failed.
Dissonant Serenity: Unless he's narrating a story, in which case he's a Large Ham, Jun remains calm and smiling in the face of most of the cast's insanity.
Eyes Always Shut: A variant, he almost always has one of his eyes closed, making him appear to constantly be giving a sly wink.
Gay Option: Parodied repeatedly. He shows no interest in Kaere unlike the other guys and seems to be unusually touchy-feely towards Itoshiki. This is all played for laughs of course, as Itoshiki is weirded out by him. And then played straight at the end, where he's suggested to have become another member of the harem.
Hot for Teacher: Itoshiki's only male student to be this towards him; the rest are grossed out by the idea. Also got a blood transfusion from Kafuka, meaning that he's also in the harem.
Japanese Christian: To be precise, he was from a family of Christians of an undisclosed sect (although signs point to Jehovahs Witness).
Large Ham: When story telling. When not, he's a pretty laid-back guy, especially in comparison to basically everyone else.
Legally Dead/I Have No Son: He was disowned by his very traditional family because he had a blood transfusion (and presumably tried to commit suicide as the cause) and his name is written as 'deceased', effectively cleaning their hands on him. On a side note, that blood transfusion is hinted to be... let's just say 'from a friend'.
The fact that he seems to be attracted to his teacher, which is outright confirmed in the ending, makes this a lot more of a tearjerker.
Nice Guy: The only person in Itoshiki's class who doesn't or hasn't killed someone, stabbed a stranger in the street, convinced others that they're God, done anything sexually immoral... in fact, he's the only real nice person in Itoshiki's class, the exception being Kafuka. Sort of.
The One Guy: Pretty much the only male student who ever does anything of particular note on a regular basis, other than Usui, who the rest of the cast almost never acknowledge. Takes on a whole new meaning when you realize he's the only guy in the class also suffering from Kafuka's possessions.
The Actual Only Sane Man: He doesn't seem to have any major quirks or defects like the rest of his classmates do, despite getting it pretty bad.
Driven home during the "Zetsubou Sensei Drawing Song" segment, where he's pretty much the only character out of dozens to actually follow the instructions properly and draw something that looks like Nozomu, apart from Abiru, who draws it with hilariously professional quality.
The Smart Guy: Compared to his classmates, he's level-headed and intelligent. Not that there's much competition, though, but he still manages to appear more competent than many adults.
Stepford Smiler: His past reveals him to have attempted suicide after his family disowned him, and is most likely as depressed as the rest of the cast. Presumably it's a mix of Kafuka's positive energy and him being an all around Nice Guy that it never shows outwardly.
The Storyteller: His stories, which me makes up on the spot, are apparently so great and heartrending that he's able to make a living off of them.
One of Nozomu's few known male students and Jin's self-proclaimed rival in storytelling. This is largely an Informed Ability — as the series went on his main gimmick became his awful, awful fashion sense.
Hot-Blooded: Though in comparison to most of the rest of the cast this is hardly that weird.
Large Ham: Unlike Jun he remains one even when not narrating a story.
Literal-Minded: Revealed to be this during one of the "Zetsubou Sensei Drawing Song" segments, where he draws exactly what the song tells him to, apparently not understanding that he was supposed to draw Nozomu.
Rummage Sale Reject: Outside school, much to Marui's neverending despair. Mostly played for laugh, but there's Freudian Excuse for it. Kino's mother was a fallen-from-grace stylist whose fashion sense deteriorated with her depression. Kino keeps wearing clothes that his mother prepared to make her happy until he starts to like those weird clothes himself.
She even overshadows Kaere at one point when they both appear in swimsuits.
Mr. Exposition: Share this status with Mikoto in several last chapters, explaining the circumstance of Kafuka's Hive Mind in class 2-He and Nozomu's reason for persisting teaching the misfits. Doubles as Secret Keeper.
OOC Is Serious Business: The instigator of a rant about serious people telling jokes, starting when she joked about going on maternity leave. Because she's a relatively serious character who's never told a joke before in the series and did it with a deadpan delivery, everybody takes it completely seriously.
Out of Focus: Has reduced appearances as both the manga and anime progressed.
There Are No Therapists: Ironically enough, since she is a therapist and is surrounded by people who need it, Chie does almost no counseling. The only person she counsels is, from time to time, of all people, Nozomu himself.
Limited Wardrobe: Just like his "old friend", he frequently wears a kimono and hakama.
Meaningful Name/Punny Name/Named After Somebody Famous: Not exactly his name, but his relationship to Nozomu. Turns out that they're more like one-day friends ("1日友") than old-time friends ("旧友"), with the author making a word play on the visual similarities between the two words. He's also named after a Buddhist sage, or specifically, his incarnation in the manga Ikkyu-san. All three Ikkyus are characterized by a quirky personality and scholarly interests.
Visual Pun: "One-day friends" ("1日友") and "old-time friends" ("旧友").
Morality Chain: Volunterily enforced this trope in order to ensure the safety of her and Chiri's pet goldfish (and possibly all of civilization).
Morality Pet: Had anyone but Chiri's sister attempted to stall her by creating mess after mess, they would've most likely been dealt with in the most inhumane way possible. But despite Chiri's frustrations concerning her sister's uncleanliness, Tane is still alive and is, to all appearances, unharmed.
That being said, there are hints that her sister does very harmful things to her, albeit unintentionally.
The Pig Pen: She manages to either create a huge mess of clutter all around her wherever she goes, or attract garbage, literal (e.g. trash) or metaphorical (e.g. drug addicts, hippies, and others at the dregs of society).
She Cleans Up Nicely: On the other hand, if she wanted to and had the time, she can groom herself up as perfectly as her sister, such as that time when she dated Nozomu. So far she's the only girl whose affection to Nozomu was reciprocated, upon the latter learning of her predicament.
When It All Began: When they were children, Chiri wanted to clean their pet goldfish by pouring shampoo onto the aquarium. Tane jumped into a pool of mud to distract Chiri and spare the goldfish (and perhaps the rest of humanity) from her murderous obsession with cleanliness.
Good Parents: Beneath all those allegations of abuse against his daughter, he turns out to be a mild-mannered, loving father who once even bought her a cake for her birthday her classmates and even teacher forgot.
It turns out he's actually a badly-behaved foreigner who happens to look like Perry, opened an unsuccessful shop, and befriended Kafuka. The irony of "Perry" having to close something at the end is not lost on the cast.