Beautiful daughter-in-law Mizuki diligently cares for her ailing father-in-law. Though frail, he remains constantly aroused, getting erect even during caregiving. Troubled by the situation, Mizuki pleads with him, insisting that "for your health, you need to ejaculate," but he refuses to listen. To ignite his desire, she uses her lustful body to seduce him. Enjoying his reactions, Mizuki continues her erotic nursing, transforming from a devoted caretaker into a depraved wife who softens his rigid demeanor with forbidden temptation.