Matsushita Tadashi is a second-year student at Kangokou High School and a frequent target of the school's many bullies, who routinely beat him up after classes. He is accompanied by his best friend, Saitou Takaki, who is also constantly harassed. As the pair grow increasingly tired of being victimized, they decide to join the titular Karate Club. The club is notorious throughout Osaka's youth gangs for training and producing the city's most hardened and toughest teenage thugs, all while maintaining the facade of a legitimate school sports club. However, upon joining, they find themselves picked on just as much, if not worse, by the club's current members.