Stepmother Airu secretly masturbates in her room during her daily cleaning routine, a place where she should be quietly alone. However, her son walks in and discovers her in the act. Seeing her in ecstasy, he is overwhelmed by an intense urge to embrace her body. As he approaches, Airu tries to resist, but she is overpowered by his forceful advance. In that moment, she can no longer hold back, trembling with desire for her son's touch. Their emotions escalate, transforming this shocking encounter into the beginning of a new, forbidden relationship.