Naoto is a housewife who lives while taking care of her husband and father-in-law. Recently, her father-in-law's dementia has become so severe that he mistakes her for his late wife... but the kind-hearted Naoto plays the role of his late wife and devotes herself to caring for her father-in-law. However, Naoto's kindness backfires, and one day her father-in-law begins to relentlessly desire Naoto's body! Naoto, sensing her father-in-law's feelings, and also fueled by her own sexual frustration, ends up having a relationship with her father-in-law... Naoto's actions with her father-in-law, who is ignored by her husband, escalate, and the two of them play with each other's bodies violently, becoming immersed in passionate sex just like a married couple...