Sae, who is a pervert at heart and has no sex with her husband, is sexually frustrated. One night, when Sae was about to go to the bathroom, she noticed light coming from her son's room. She opened the door and peeked inside, and saw her son masturbating with his cock completely exposed. From that day on, Sae could not concentrate on anything other than thinking about her son's hard cock, and she ended up having a forbidden relationship with her son...