High-libido masochist Satomi is a young wife left unsatisfied by her passive husband, so she begins a passionate affair with his boss. Meanwhile, her perverted live-in father-in-law keeps tying her up and making her cum as part of his sadistic training. Jealous of her affair, he escalates the bondage until she completely submits as his sex slave, writhing in pleasure and climaxing while servicing three cocks at once.