While staying at his wife's family home ahead of her delivery, Yokoyama becomes obsessed with the voluptuous body and suggestive behavior of her now-adult sister, Minami. He starts using a borrowed security camera to spy on her, then watches her bring one of his male subordinates into her room and ride him for her own pleasure. The sight sends his suppressed desire spiraling out of control. Busty star Minami Ayase makes her Madonna debut in a harrowing forced-sex scene, resisting the assault even as her body gradually responds to the pleasure.