Yuko takes on the responsibility of caring for her father-in-law while her stepmother and a friend go on a hot springs trip. A hardworking and diligent woman, she dedicates herself to his care, but soon finds herself subjected to sexual harassment from her father-in-law, who has long desired her body. Initially confused and hesitant, she is unable to resist his increasingly aggressive advances, eventually being forced into a sexual relationship. Burdened with guilt toward her husband and stepmother, Yuko becomes emotionally entangled with her father-in-law, reduced to nothing more than a plaything for his desires.