Four years into her marriage, Momoka finds her relationship with her husband growing cold due to his erectile dysfunction. Sensing her distress, her father-in-law, Tatsuo, sees an opportunity to satisfy his own desires and possess her uninhibited body. One day, Tatsuo pretends to accidentally ingest the erectile medication Momoka prepared for her husband, deliberately throwing her into panic. Exploiting her vulnerability, he pleads with her to relieve his erect cock, and obediently, she touches him and brings him to ejaculation. Awakened by the pleasure, Tatsuo soon exposes his erect penis again, demanding new experiences from Momoka.