[[quoteright:280:http://static.tvtropes.org/pmwiki/pub/images/katteni_kaizo_7636.jpg]]
->''[[AnimeThemeSong You can upgrade me however you like.]]''

One day, 17-year-old high school student [[{{Cloudcuckoolander}} Kaizo Katsu]] woke up in a lab, surrounded by vials of chemicals and utensils, and with defibrillator electrodes on his nipples. Coming to the conclusion that, on the brink of death, he was turned into a {{cyborg}} by "genius" Suzu Saien, he takes over the Science Club, of which Suzu is President, turning it into the Science Investigation Club, a group with absolutely no objectives, goals or point besides being an outlet for Katsu's wackiness -- often at the expense of another member, Chitan Tsubouchi, who Kaizo names his peon.

But he's not always been this way. Kaizo used to be a perfectly sane ChildProdigy, at least until ten years ago, when his childhood friend [[OnlySaneMan Umi Natori]] kicked him off a climbing frame and he hit his head ''hard'' -- so hard he went completely loopy, developed a fascination for [=UFOs=], ghosts and the like, and unintentionally blew up his alma mater Genius Cram School, releasing the collective insanity and quirkiness of all the very specialized geniuses of the school onto the world.

A {{Shonen}} {{Manga}} by KojiKumeta (of ''SayonaraZetsubouSensei'' fame) that ran between 1998 and 2004 before being canceled for various reasons.

Came within an inch of having an anime adaption, but ended up being rejected. Fortunately, Creator/StudioShaft (where Kumeta's better-known manga was adapted) is also giving it a second lease of life as an {{OVA}} series.

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!!Tropes appearing in ''Katteni Kaizo'' include:
* AccidentalAthlete: Played for laughs. Chitan is actually a god of soccer, and had he pursued this talent he could have rocked the planet, but he's only interest in trains, and his potential is wasted.
* AmbiguouslyBrown: Satan, though he might just be very tanned.
* ArtEvolution: KojiKumeta's style changed in the interim between this and ''SayonaraZetsubouSensei''.
** The anime goes through it too, at the same sort of pace as the manga did.
* AuthorAvatar: His first appearance, known as 'The Neighbourhood Mangaka Who Doesn't Sell'. Apparently likes to [[NippleAndDimed draw nipples on women from old manga]] and [[DrivenToSuicide attempt suicide when]] [[MythologyGag things don't go his way]].
* BrainBleach: Seeing [[FanDisservice the principal pole dancing in a thong]] makes Kaizo, Suzu and Umi erase that day from their memories.
* BreakingTheFourthWall: A few times, though not nearly as much as [[SayonaraZetsubouSensei its successor]].
* BrickJoke: One starts when a woman gets sealed behind a wall, it didn't pay off for '''seven years''' and when it did it was in a completely different [[SayonaraZetsubouSensei work]].
* ButtMonkey: Chitan Tsubouchi all the way.
* CameraAbuse: Kaizo kicks Chitan head first into the camera during the OnceAnEpisode OpeningNarration.
* CampGay: Mario "Fashionable" Biyoshino
* ChildhoodMarriagePromise: Umi and Kaizo made one. Then she accidentally gave him brain damage.
* ChristmasCake: Yoshiko-sensei. Kaizo likes to call attention to it, much to her distress.
* {{Cloudcuckoolander}}: Kaizo lives, breathes and sweats this trope.
** TheCuckoolanderWasRight: [[OnceAnEpisode Every time.]]
* CovertPervert: Turns out Kaizo is one, and even started a gang devoted to intense fantasising about various sexy situations, where he gained legendary status for his imaginative powers.
* CramSchool: Kaizo went to one for "Geniuses" before he blew it up. His fellow former pupils pop up from time to time.
* CuteLittleFangs: Jun has one.
* ADateWithRosiePalms: Depicted pretty often. The ending song gives Chitan superpowers from doing this.
* DisappearedDad: Quite literally, since Kaizo's dad is a {{ninja}} who deliberately hides from them.
* DissonantSerenity: Nothing has the power to faze Suzu Saien.
* DistractedByTheSexy: In the [[BeachEpisode Pool Episode]] everyone is too distracted by [[ItMakesSenseInContext Kaizo's outboard mini-motor tearing up the girls swimsuits]] to pay attention to Chitan showing off.
* DoItYourselfThemeTune: Though her character is only a minor one, Creator/StudioSHAFT stalwart Creator/RyokoShintani sings the end tune.
* EmbarrassingFirstName: Yamada-san has one. She hates it so much that anyone who tries to reveal it faces death.
* EnfanteTerrible: Flashbacks show us Umi was one. Kaizo explains that she took children's games too literally (such as actually performing surgery when PlayingDoctor).
* GagPenis: Chitan is outright stated to be well hung, especially given his size...
* GenreBlindness: Umi is unable to read the mood of situations so makes everybody awkward. At Kaizo's request she undergoes rigorous training to correct it.
* GivingSomeoneThePointerFinger: Kaizo does this constantly, and always in the most dramatic way possible.
* {{Gonk}}: Every single VillainOfTheWeek.
* HotTeacher[=/=]HelloNurse: Yoshiko-sensei, despite being a ChristmasCake.
* HomoeroticSubtext: Played up between Kaizo and Satan.
* IdiotsCannotCatchColds: Umi uses this theory as hope that Kaizo might become a prodigy again when he catches a cold after losing a towel-rubbing match.
* ItMakesSenseInContext: Pick a chapter, any chapter, then look at the middle and imagine yourself explaining what's going on to someone else.
* KaleidoscopeEyes: A weird example, as the main characters seem to swap between brown, green and blue eyes every episode.
* KansaiRegionalAccent: Jun gets teased for having this.
* KidAnova: Somehow Kaizo has managed to date most of his female classmates, including [[HotForStudent his teacher]] at one point.
* KissingUnderTheInfluence: Invoked. Umi is accused of being pregnant. Suzu convinces Kaizo he fathered the child after taking advantage of Umi when he was drunk. Things quickly get out of hand.
* LargeHam: Kaizo all the way. Many of his fellow Cram School students are also this.
* [[MagicSkirt Magic Skirt/Labcoat]]: Played with. During the end theme for the OVA, initially Umi and Suzu's hair follows the rule of gravity while their clothes don't. Then after a couple seconds, the clothes start being affected by gravity as well. Shots change before the [[PantyShot inevitable]] though. Kinda.
* MegatonPunch: Kaizo thinks he can perform one (though it turns out Chitan is just really delicate). In the anime opening he destroys a tank with one hit.
** Umi demonstrates a particularly violent one in episode 5.
* MsFanservice: Suzu, who is notably described as having an "ecchi-body". Occasionally Yamada-san or Yoshiko-sensei fill in for her.
* NakedPeopleAreFunny
* NamesToKnowInAnime: And most of them Creator/StudioShaft regulars.
** Creator/TakahiroSakurai: Kaizo Katsu
** Creator/EriKitamura: Umi Natori
** Creator/AkiToyosaki: Suzu Saien
** Creator/ChiwaSaito: Chitan Tsubouchi
** Creator/YuiHorie: Yamada-san
** Creator/ShinichiroMiki: Mario-sensei
** Creator/FumihikoTachiki: Narrator
* NearDeathExperience: Kaizo sees the anatomy model knocking him out as this, even though he wasn't that badly hurt. When he wakes up he's a cyborg.
* NerdGlasses: Chitan of course.
* NoIndoorVoice: The mysterious (naked) poets.
* NonUniformUniform: Kaizo's ever present purple stripy t-shirt.
* OnlySaneMan: Umi. [[spoiler:At least until it turns out that she's just as nuts as Kaizo]].
* OnTheNext: Gleefully subverted. Kaizo just stands there in some random setting (like a mansion or the train station) doing a voice over that literally consists of "Next time - something, something and something else."
* PeekABangs: Kaizo, mostly.
* PolarOppositeTwins: Chitan and Satan.
* PoolEpisode: With [[ClothingDamage disappearing]] swimsuits!
* ProgressivelyPrettier: Satan grows taller and more {{bishounen}} over time. Chitan inverts this by becoming shorter and uglier.
* PunnyName: Kaizo's first name can be interpreted as 'cyborg'. His last name can mean 'victory' which befits a HotBlooded hero.
** 'Saien Suzu' is pronounced similarly to the English word 'science' in a Japanese accent.
** The main characters attend 'Torauma' High School, which is pronounced roughly the same as 'trauma'. [[spoiler:This becomes appropriate given the TwistEnding.]]
* RailEnthusiast: Chitan is a train {{otaku}}, often carrying a model one around with him. His love of trains is apparently his only talent.
* RedBaron: For some reason Yamada-san is always referred to as "The Beautiful, Popular [[ClassRepresentative Class President]] Yamada-san" whenever she makes an appearance.
* ReferenceOverdosed
* RefugeInAudacity: Much of the humor comes from the whole thing going ''so far'' into the obscene.
* RelationshipUpgrade: [[spoiler:Kaizo and Umi]] end up at least living in the same house, although the doll wedding scene could imply something more.
* SayItWithHearts: Apparently doing this at the office is sexual harassment.
* {{Seppuku}}: Chitan is forced to commit this in episode 4 as punishment for being too eccentric.
* SeriousBusiness: Whatever the specialty/quirk of any of any [[DropInCharacter Drop-In Characters]], it'll be serious business for them. Heck, at one point there's an entire village for which konnyaku (a type of gelatinous desert) is SeriousBusiness.
* ScarfOfAsskicking: Kaizo's imaginary badass cyborg action hero counterpart wears one.
* ShipTease: Umi blatantly likes Kaizo, and Kaizo never outright denies liking her back. Surprisingly [[spoiler:Yamada-san and Satan]] as well.
* ShoutOut: Chitan is thinking of [[Franchise/MetalGear Big Boss]] when discussing camouflage, only for both to find out that [[ItMakesSenseInContext camouflage is not for disguising]].
* SoundtrackDissonance: The opening theme makes it seem like a standard {{shounen}} action/romance anime. The ending theme leans more towards {{shojo}}.
* StalkerWithACrush: Chitan becomes one for his co-worker Arumi, who realises she has a stalker and much to his delight seeks comfort from Chitan, not knowing that it's really him.
* StuffBlowingUp: Whether they be caused by mixing dangerous chemicals, toilet bombs or kicking a football, explosions are abound.
* TeenIdol: Suzu and Jun (previously).
* ThemeNaming: 'Natori Umi', 'Haku Arumi' and 'Chitan' are all named after metals - sodium, aluminium and titanium respectively.
* [[spoiler:ThroughTheEyesOfMadness]]
* TooKinkyToTorture: The school principal is a self-named masochist and has his own dungeon beneath the school.
* TrademarkFavouriteFood: Yamada-san and yakisoba bread.
* {{Tsundere}}: Umi displays these tendencies, particularly when it's Kaizo she's yelling at/beating up. Otherwise she's just violent.
* TwistEnding: [[spoiler:Turns out ''everything'' was just a fantasy created by Umi and Kaizo, two asylum patients who were allowed to construct their own little world as part of their therapy, and Suzu was their therapist. The finale is them finally leaving the hospital and moving in together.]]
* UnbuiltTrope: The premise sounds an awful lot like [[LightNovel/HaruhiSuzumiya a certain popular series]], but not only was it made before it, but [[spoiler: the main character is really just an insane whackjob and none of the weirdness going on is actually happening.]]
* UnCancelled: There was supposed to be an anime adaptation when the manga was still running, but then Shogakukan pulled the plug; now thanks to the kanzenban releases and Creator/StudioShaft, it's getting a second chance at life as an OVA.
* UnknownRival: Poor Jun, Suzu doesn't (or pretends not to) remember all the cruel stuff she did to her.
* UnlimitedWardrobe: Outside of school the characters are shown in various (and often detailed) casual outfits, something which Kumeta continued to do in ''SayonaraZetsuboSensei''.
* VoodooDoll: Thanks to all her grudges, [[spoiler:Umi]] owns a lot of these.
* [[WackyWaysideTribe Wacky Wayside Cram School Student]]: The genius pupils from Kaizo's old school. They show up to make funny stuff happen.
* WeCanRebuildHim: The explanation Kaizo comes up with for being made into a cyborg is that he was attacked by some monster and it was the only way to save his life. In truth, he was knocked out by a falling anatomy model and was just zapped back to consciousness.
* XMeetsY: Some sort of a GenderFlipped version of ''SuzumiyaHaruhi'' on drugs; alternatively, Haruhi is a GenderFlipped version of this on antidepressants.
* YoungerThanTheyLook: One chapter focuses on a mob of teens who look like middle aged men trying to get revenge on Kaizo, who gave a nickname reflecting this fact to their leader.
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