Suddenly, the niece comes to stay alone at the house of her uncle who lives alone! He is tempted by her defenseless appearance after the bath! He is already suffering from a lack of women, so he can't stand the young woman! When he pulls out his erect penis as a joke, she doesn't refuse, saying, "I know. You mean I should thank you, right?" Even though he knows it's not good between relatives, his crotch is honest...! He lets his momentum take over and indulges in pleasure in forbidden sex!