Yumi, a married woman, grows increasingly frustrated with her unemployed brother-in-law, Keiji, who does nothing but shut himself away at home. When she turns to her husband for help, he proves completely unreliable, instead coddling Keiji like a spoiled child. One day, Yumi falls ill with a bad cold and takes to her bed, leaving her weak and vulnerable. Seizing the opportunity, Keiji, who has long resented his nagging sister-in-law, pounces without hesitation and forcefully overpowers her. Unable to resist due to her weakened state, Yumi's voluptuous body is taken against her will. But this is only the beginning. Keiji's obsessive revenge, fueled by resentment, escalates further from this moment on.