Ever since he was a child, he secretly watched his parents' intimate moments and saw them bathing together. Over time, he developed a habit of masturbating while sniffing his mother's underwear. One day, the mother catches her son sneaking into her room and begins teasing him by performing masturbation in front of him, saying she wants to understand his feelings. She allows him to touch her body, and their relationship takes a drastic, irreversible turn.