Ayako, who divorced her husband a year ago, explained to her friends that her husband had been cheating on her, but in fact there was a real reason that she could never tell anyone. That was that she had fallen into a physical relationship with her son Satoshi that went beyond the relationship between mother and son, which is something that can never be forgiven. Moreover, rather than trying to end this abominable relationship, Ayako tries to deepen it, continuing her immoral sexual encounter with Satoshi as long as time allows, pressing her lips together and entwining her tongue.