Eri, his father's new wife. (Why would such a beautiful woman end up with my father...?) Shinichi, his son, had begun to think of Eri, who was too young and beautiful to be called his stepmother, as a member of the opposite sex at some point. However, an incident occurred that seemed to toy with Shinichi's ulterior motives. Eri had been inviting men into her home while the family was away and repeatedly cheating on her. Shinichi happened to witness this and was filled with anger, but at the same time, a vile thought crossed his mind...