After his aunt Mio had a fight with her husband, she decided to live with Keisuke for a while. Mio admired Mio and had feelings for her as a member of the opposite sex. While living there, Keisuke was excited by her big breasts, when he found Mio's panties left in the bathroom. He couldn't help but masturbate, but Mio witnessed it. Mio, who has a free-spirited personality, came to Keisuke while he was taking a bath in the middle of the night and gently stroked his penis before inserting it into her vagina.