Jun's mother has been away on a hot spring trip with friends from the Hawaiian club for two days, and his father is on a business trip for two nights and three days, so he will be left alone at home from tonight. Then he gets a call from his mother's younger sister, Chiaki... His aunt, Chiaki, is visiting Tokyo and says she wants to stay at her sister's house because of a friend's arrangement... That night, Jun unexpectedly ends up spending the night alone with his aunt... Jun, who is still a virgin, sneaks a peek at his aunt taking a bath, but is caught by his aunt. The aunt forces Jun into the bath and makes him touch a woman's body, stimulating his sexual desire and teaching him how to caress breasts...