Momo, a female student who serves as a disciplinary committee member, visits the house of her shut-in classmate, Yusei. - However, the man who shows up is a man named Hirai, an active yakuza who has been friends with Yusei's father Kenta since he was a yakuza, and who uses this house as an office and plays shinogi. - Kenta, guided by Hirai, tells Momo, ``Yusei is trash, so we should stop seeing each other,'' but Momo doesn't accept his words and ends up meeting Yusei instead. - As soon as Yusei sees Momo, he throws a grudge against her. - And Kenta and Hirai also participated...