The Karate Club first appeared when Yukari Sendo and Kokoa Shuzen were looking for places where they could become stronger. They, however, were refused admission to the club becuase "pretty little girls didn't suit the club" and their young age.
The recruiter for the club then tells them that, if they can break a gravestone, they can join the club but it would cost them 1000 yen for one attempt. Having no such money, Yukari gloomy suggests that they try the other Martial Art Clubs.
Later on, the recruiter is seen asking for any challengers to try and break the gravestones and win 50000 yen. It is then revealed that they are cheating, as the gravestones the challenger use are much harder than ordinary gravestones. An older Kokoa (thanks to Yukari's Growing Drops) comes up and tells him that she'll pay the fee later before she breaks 13 gravestones in one blow, setting a new record and winning the money.
The recruiter then comes up and asks Kokoa to join the club. Inside, however, he is thinking about how he would "use her for the worth she took". When she says they're weak, both the recruiter and his brother attempt to fight her, only to be defeated in an instant.
It is then that Haji and other Third Grade members from the Karate Club appear, asking her if she had been a little rough to his juniors and saying not to underestimate his club. Saying that she would join them if they could beat her, everyone is then shocked when Kokoa suddenly shrinks. Then, realizing what happened, they appeared behind Kokoa and cracked their knuckles.
Haiji feints an attack on Kokoa, which then hits the wall behind her and cause a small explosion. He then tells her he is the captain of the club and that anyone who mocked it wouldn't be pardoned. He then picks her up and says that she is cute (making Kokoa accuse him of being a lolicon) before the recruiter tells him to punish her.
With a stern look, Haiji tells them that he wouldn't have them expose their shame "any more than this" and sends them running.
Later on, Haiji comes to find some of the bullying "idiots" of his club in a brawl with what appears to be a group of children. They all then turn on him, where he admits he's a lolicon, before they defeat him with Child-Only-Combination-Secret-Super-Move: Rainbow Destroyer.
News of the Karate Club's defeat by the Newspaper Club spread around campus and then reduced the number of applicants into the Newspaper Club to zero.
- Haiji Miyamoto (Current/Former Captain)