To support her son Koichi's dream of entering a national university, mother Yuna has raised him strictly since he was young. Whenever his grades slipped even slightly, she would scold him harshly with piercing words, forcing him into relentless study. Harboring growing anger and resentment toward his mother, Koichi begins to devise a plan. Seizing the opportunity while his father is away on a business trip, he plots the nightmarish act of tying her up and raping her. This film confronts the turbulent emotions and inner conflicts beneath the shifting bond between mother and son.