Rei Komatsu is 35 years old. She lives with her husband and son. As she listens in on her son's phone conversations, Rei is overcome with indescribable jealousy at the conversation between her son and his girlfriend, and masturbates while fantasizing about having sex with her son. Her son witnesses his mother in this state. One day, when she peeks into her son's room, she sees him masturbating while having phone sex with his girlfriend while looking at a porn magazine. Rei gives in to the heat of her body, and her desire for her son's body leads her to forcibly have a physical relationship with him. The perplexed son is also drawn to the charms of the mature woman's sensuality and becomes obsessed with sex with his mother.