In the fourth year of her marriage, Momoka's husband's erectile dysfunction has made their marriage difficult. When her lustful father-in-law, Tatsuo, finds out, he plots to somehow enjoy her voluptuous body in order to satisfy his own sexual desire... One day, Tatsuo pretends to accidentally take the erection pills Momoka had prepared for her husband. Seeing her in a state of agitation, he begs her to calm down his erect penis... Momoka does as she is told and strokes him with her hand, bringing him to orgasm. Having gotten a taste for this, Tatsuo shows off his erect penis again...