Two years ago, after her husband became impotent, Eriko had been living in constant torment. One day, she casually peeked into her son's room and found him engrossed in masturbation. Seeing his erect penis for the first time in a long time, Eriko couldn't help but tempt him, saying, "Masturbation isn't enough to satisfy you, is it? Why don't you... do it with Mommy?" Unable to resist his mother's advances, the son ended up having sex with her, and things quickly escalated...