After losing her husband, mother Momoko raised her son Kazuya all on her own. However, Kazuya's academic performance showed no signs of improvement, and as the stress of parenting mounted, Momoko's sexual frustration grew day by day. One day, she got her hands on a confiscated vibrator belonging to Kazuya's friend, Shunsuke, and unable to resist, she gave in to masturbation. By chance, Shunsuke witnessed the entire scene. Momoko's self-pleasure ignited his own sexual desire, and before long, she was gripping his erect penis, hungrily stroking it. This moment, born from the explosion of Momoko's pent-up stress and longing, became the catalyst for a new emotional conflict within her.