Concerned about her father-in-law's worsening dementia, Akari Mitani's husband suggests a family trip to the nostalgic place where they once stayed with his late mother. But upon arriving at the inn, the father-in-law, in a confused state of mind, begins calling out for his deceased wife, Youko, and acts increasingly erratic. He demands feeding assistance, but it quickly becomes clear this is no ordinary caregiving—he begins passionately kissing Akari, entangling his tongue with hers, and aggressively pursuing a physical relationship. Torn between compassion for her stepmother's memory and concern for the man's deteriorating condition, Akari ultimately gives in and engages in an incestuous affair with her father-in-law.