By chance, Tatsuro ends up living with his aunt, Hisayo, and is worried about her being too wild about sex. He didn't even try to hide her underwear and showed off her chest and crotch, and every night he masturbated her while making her moans and moans. Tatsuro spends those days in agony, unable to hide his confusion. Then, one night, while Tatsuro was taking a bath, Hisashiro suddenly came in. She ignores Tatsuro who is surprised.