During her husband's long-term overseas assignment, Ryo Sayo has been living alone with her son for the past three years. One day, her son's friends Akira and Naoya come to visit. Naoya accidentally discovers Ryo indulging in masturbation and, losing control, is drawn to her alluring mature body. Initially resisting, Ryo gradually gives in as she rediscovers pleasure she hasn't felt in years, torn between confusion and desire. Deeply affected by the encounter, Naoya later finds himself seeking out similar experiences again.