You can upgrade me however you like.
One day, 17-year-old high school student 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 Child Prodigy, at least until ten years ago, when his childhood friend 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 Shōnen Manga by Koji Kumeta (of Sayonara, Zetsubou-Sensei fame) that ran from 1998 to 2004 in Weekly Shonen Sunday before being canceled for various reasons.
Came within an inch of having an anime adaption, but ended up being rejected. Fortunately, Studio Shaft (where Kumeta's better-known manga was adapted) gave it a second lease of life as a six-episode OVA series in 2011.
Tropes appearing in Katteni Kaizo include:
- Accidental Athlete: 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.
- Author Avatar: His first appearance, known as "The Neighbourhood Mangaka Who Doesn't Sell". Apparently likes to draw nipples on women from old manga and attempt suicide when things don't go his way.
- Brain Bleach: Seeing the principal pole dancing in a thong makes Kaizo, Suzu and Umi erase that day from their memories.
- Brick Joke: 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 work.
- Camera Abuse: Kaizo kicks Chitan head first into the camera during the Once an Episode Opening Narration.
- Childhood Marriage Promise: Umi and Kaizo made one. Then she accidentally gave him brain damage.
- Covert Pervert: 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.
- Cram School: Kaizo went to one for "Geniuses" before he blew it up. His fellow former pupils pop up from time to time.
- Disappeared Dad: Quite literally, since Kaizo's dad is a Ninja who deliberately hides from them.
- Distracted by the Sexy: In the Pool Episode everyone is too distracted by Kaizo's outboard mini-motor tearing up the girls swimsuits to pay attention to Chitan showing off.
- "Do It Yourself" Theme Tune: Though her character is only a minor one, Studio SHAFT stalwart Ryōko Shintani sings the end tune.
- Embarrassing First Name: Yamada-san has one. She hates it so much that anyone who tries to reveal it faces death.
- Enfante Terrible: Flashbacks show us Umi was one. Kaizo explains that she took children's games too literally (such as actually performing surgery when Playing Doctor).
- Gag Penis: Chitan is outright stated to be well hung, especially given his size...
- Genre Blindness: Umi is unable to read the mood of situations so makes everybody awkward. At Kaizo's request she undergoes rigorous training to correct it.
- Giving Someone the Pointer Finger: Kaizo does this constantly, and always in the most dramatic way possible.
- Idiots Cannot Catch Colds: Umi uses this theory as hope that Kaizo might become a prodigy again when he catches a cold after losing a towel-rubbing match.
- It Makes Sense in Context: Pick a chapter, any chapter, then look at the middle and imagine yourself explaining what's going on to someone else.
- Kaleidoscope Eyes: A weird example, as the main characters seem to swap between brown, green and blue eyes every episode.
- KidAnova: Somehow Kaizo has managed to date most of his female classmates, including his teacher at one point.
- Kissing Under the Influence: 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.
- Magic Skirt: 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 inevitable though. Kinda.
- Megaton Punch: 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.
- Ms. Fanservice: Suzu, who is notably described as having an "ecchi-body". Occasionally Yamada-san or Yoshiko-sensei fill in for her.
- Near-Death Experience: 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.
- On the Next: 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."
- Progressively Prettier: Satan grows taller and more bishounen over time. Chitan inverts this by becoming shorter and uglier.
- Punny Name:
- Kaizo's first name can be interpreted as 'cyborg'. His last name can mean 'victory' which befits a Hot-Blooded 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'. This becomes appropriate given the Twist Ending.
- Rail Enthusiast: Chitan is a train otaku, often carrying a model one around with him. His love of trains is apparently his only talent.
- Red Baron: For some reason Yamada-san is always referred to as "The Beautiful, Popular Class President Yamada-san" whenever she makes an appearance.
- Refuge in Audacity: Much of the humor comes from the whole thing going so far into the obscene.
- Relationship Upgrade: Kaizo and Umi end up at least living in the same house, although the doll wedding scene could imply something more.
- Serious Business: Whatever the specialty/quirk of any of any 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 Serious Business.
- Ship Tease: Umi blatantly likes Kaizo, and Kaizo never outright denies liking her back. Surprisingly Yamada-san and Satan as well.
- Short-Runners: The OVA ran for six episodes.
- Shout-Out: Chitan is thinking of Big Boss when discussing camouflage, only for both to find out that camouflage is not for disguising.
- Soundtrack Dissonance: The opening theme makes it seem like a standard shounen action/romance anime. The ending theme leans more towards Shōjo.
- Stalker with a Crush: 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.
- Stuff Blowing Up: Whether they be caused by mixing dangerous chemicals, toilet bombs or kicking a football, explosions are abound.
- Theme Naming: 'Natori Umi', 'Haku Arumi' and 'Chitan' are all named after metals - sodium, aluminium and titanium respectively.
- Too Kinky to Torture: The school principal is a self-named masochist and has his own dungeon beneath the school.
- Tsundere: Umi displays these tendencies, particularly when it's Kaizo she's yelling at/beating up. Otherwise she's just violent.
- Twist Ending: 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.
- Unbuilt Trope: The premise sounds an awful lot like a certain popular series, but not only was it made before it, but the main character is really just an insane whackjob and none of the weirdness going on is actually happening.
- Un-Cancelled: 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 Studio Shaft, it got a second chance at life as an OVA mini-series.
- Unknown Rival: Poor Jun, Suzu doesn't (or pretends not to) remember all the cruel stuff she did to her.
- Unlimited Wardrobe: Outside of school the characters are shown in various (and often detailed) casual outfits, something which Kumeta continued to do in Sayonara, Zetsubou-Sensei.
- We Can Rebuild Him: 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.
- Younger Than They Look: 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.
