since her husband went on a business trip, yuko has been suffering from severe sexual frustration. her masturbation becomes more intense, and she doesn't even notice her son watching. seeing yuko like this, her son offers to comfort her. yuko decides to fall into a taboo world with her son, mistaking his kindness. but yuko, who has shed her mother's mask and fully embraced her desires, is so lewd that even her son is confused.