The Mido-gumi is the largest yakuza organization in the Kansai region. Born as the only son of its boss, Tsuyoshi Mido was raised with the expectation that he would naturally inherit the syndicate one day.

Despite being a high school student, his behavior is atrocious, and he is an incredibly strong fighter. Combined with his father's reputation, he is a presence that even the teachers at school dare not challenge.

Lately, Mido has set his sights on Guest, a student in the same class.