Kahoru lives in a small rural house with her family as a mother of two children. Her eldest son, Kenichi, attends a prestigious university in Tokyo and excels both academically and socially. In contrast, her younger son Kenji constantly feels inferior due to being compared with his older brother. Desperate for his mother's recognition and affection, Kenji secretly witnesses a sexual encounter between his parents inside the family's private room. Shocked by the sight of his mother moaning, "I can't live without this~," Kenji becomes consumed by the obsessive thought that possessing a penis will make him indispensable to her. Driven by this desire, he begins a twisted journey that irreversibly alters their lives.