Working at a small obstetrics and gynecology hospital in Tokyo, Rio Rukawa is known for her kindness, laughter, and ability to brighten up those around her. However, she has a secret that even her close colleagues are unaware of: she seduces husbands who visit the hospital, hiding it from their pregnant wives. Men whose wives refuse sex until after childbirth, leading to pent-up sexual desire and stress, easily succumb to Rio's temptation in the sperm collection room, hospital room, or even right next to the delivery room where their wives are in labor. As Rio watches the men's faces with satisfaction, she smiles sweetly. "I just feel like being mean when I see happy couples..." This set includes four episodes of adultery within the hospital walls.