A seemingly ordinary household consisting of mother Risa (Murasaki), her son Kazuki, and younger sister Fumika (Morino) has its life suddenly upended by an unexpected event. A phone call from Kazuki's homeroom teacher reveals the shocking truth that he stole a female classmate's underwear. With college entrance exams approaching, the scandal threatens his future. Taking responsibility, the mother offers her body to the teacher. But when Kazuki discovers the truth, he is stunned and erupts in rage. Blaming his mother, he drives a wedge into their family bond—leading to intense domestic conflict and a shocking conclusion as familial ties are pushed to the breaking point.