Chiharu and Kazuaki visit their friend Natsuo's house, but Natsuo is absent, leaving only his older sister Minako, who recently went through a divorce. Feeling lonely, Minako had been indulging in masturbation when Chiharu suddenly appears. Surprised by his arrival, she nonetheless becomes aroused at seeing a man after so long and, overwhelmed by uncontrollable desire, begins touching herself. Witnessing the scene, Kazuaki later learns about the incident and finds himself wondering what will happen next.