New teacher Ko visits the home of her student, Hiroaki, who has been refusing to attend school. She is greeted by Hiroaki's father, Kenta. Following his invitation, she is led into Hiroaki's room—but the moment she steps inside, the door is locked behind her. Suddenly overpowered, Ko is pinned down and assaulted by both Hiroaki and Kenta. Soon, Hiroaki's older brother Daisuke and their uncle Noboru, an active yakuza member, arrive with his subordinates, joining in and reducing Ko to a broken, humiliated state. Gradually, Ko loses all sense of her role as a teacher, transforming completely into a masochistic sex slave.