Aya Masuo plays Miyou, a mother deeply devoted to her son Keita. Despite his growing age, she still shares the bath with him. One day, when Miyou enters Keita's room, she catches him reading an adult magazine, hastily trying to hide it. Saying "It's natural at your age," she surprises him by pinning him down. Keita has long harbored intense feelings for his mother that go beyond filial love, and he awkwardly expresses his uncontrollable desire. Though shocked at first, Miyou gradually accepts his emotions. The story unfolds as their complex feelings intertwine, giving rise to a new, forbidden relationship.