After divorcing her abusive husband, Chisato lived peacefully with her son. However, her pent-up sexual desires could only be satisfied by nightly masturbation. One day, she was threatened by landlord Kurahara and forcibly raped. Though resisting at first, her body responded to the long-lost sensation of sex. That night, she accidentally saw her son's erect cock, reigniting the heat within her body. Exposed to these unfamiliar thrills, her mind and body gradually began to waver.