Due to her husband's one-month business trip, daughter-in-law Ayumu is left to care for her father-in-law. Staying under the same roof, the cruel stepfather's hidden desires begin to surface as he takes advantage of the young woman living with him. As their cohabitation continues, he grows increasingly obsessed with Ayumu—feeding her mouth-to-mouth, urinating on her, escalating their intimacy even during showers. Whenever Ayumu lets her guard down, he thrusts himself inside her, giving in to his urges. This is the forbidden, taboo story of carnal lust that defies age and family bonds.