My aunt Mio had a fight with her husband and ended up living at Keisuke's house for a while. For Keisuke, Mio was the person he admired, and she had feelings for him as a member of the opposite sex. Keisuke finds Mio's panties left in the bathroom while he is living with excitement over the cleavage of her big breasts. He involuntarily masturbates, but Mio witnesses it. Mio, who has a free-spirited personality, takes a bath late at night.