Yumi came to a hot spring with her son on this day. Her son who cares about her recently divorced Yumi brought her to the hot springs. So Yumi tried to enter the bath, but she accidentally entered the changing room of the men's bath and peeked at her son's change of clothes. There she finds that Yumi sees her son as a man. Even though she thinks she has to control herself, she can't help herself and she ends up having an affair with her son...
