father's lover

Even though my mother is hospitalized, my father continues to have a relationship with his mistress, Shizuka, even paying her to do so. The son, Seiji, feels angry at his father, and at the same time falls in love with Shizuka's beauty. One day, Shizuka's father leaves and leaves Shizuka alone in the house. Then, Shizuka approaches Seiji's young and strong body...