Kazusa has been married for two years and living peacefully with her father-in-law Tadao for the past six months. One day Tadao is bedridden by a back injury. Having gone without a woman since his wife died, he gets an involuntary erection whenever Kazusa touches him while helping. Kazusa is sexless with her husband and cannot take her eyes off her father-in-law's crotch. Eventually, under the excuse of caregiving, they press their bodies together. Their hidden frustration erupts into afternoons spent tangling tongues whenever her husband is away.