Five years after separating from her husband, Kaoru had been filling the emptiness of daily life through masturbation. However, as she grew accustomed even to this act, she began craving new excitement. That's when her attention turned to her son, Kazushi. Kazushi had secretly watched his mother's behavior for years, and one day, being taken by his mother caused all his pent-up emotions to erupt uncontrollably, sparking the beginning of a new relationship.