A single mother named Nina has raised her son alone. When he got a job and encouraged him to move out, he refused. She decided to take him on a hot spring trip to convince him. During their vacation, her son suddenly confessed that he had always liked her more than his girlfriends... ever since they were little. As she listened to his longtime feelings, she gradually became serious about him. Seeing her son feeling bad because of her, she thought she was just showing some maternal love... but it turned out to be more intense than expected. They made a promise to do it once, but couldn't resist each other's passionate desires. This taboo story tells of a mother and son who continue to mate despite their initial agreement.
