Soon after marrying, a woman learns that her husband's adult son Kenta will be living with them. He refuses to work, stares at her body and spends every night with a beloved sex doll named Sayaka. Her husband ignores her concerns. While cleaning Kenta's filthy room in his absence, she accidentally breaks the doll. Kenta catches her, then channels his grief and rage into an assault that forces his stepmother to become its replacement.