Ever since her husband left for work, Yuko has been deeply sexually frustrated. Her masturbation has become more and more extreme, and she is so absorbed in it that she doesn't realize her son is watching her. Unable to bear seeing Yuko like that, her son embraces her and offers to comfort her. Realizing that this is his way of showing his kindness, Yuko decides to fall into a world of immorality with her son. However, after she sheds the mask of a mother and unleashes her womanly desires, Yuko becomes so promiscuous that even her son is confused...