One day, Shiori, an honor student, visits the home of her shut-in classmate, Yusei. She is greeted by her father, Koji. At first glance, he appears to be a kind-hearted middle-aged man, but in reality he is a former yakuza who has his hands in various shady businesses. Shiori is shown into Yusei's room, where she is gang-raped by Yusei and Koji. Yusei is also an accomplice of Koji and the others, and he didn't go to school because he enjoyed these activities. Too scared to resist, she just lets them do whatever they want, but gradually her masochistic tendencies begin to emerge...