Koji, who was visiting his childhood friend's house, witnessed his friend's mother, Reika, indulging in masturbation. Koji, who had admired Reika since he was a child, secretly took a picture of the scene to use as wanking material... But as he enjoyed looking at the image over and over again, evil feelings began to grow. "If I corner her by showing her this picture, maybe Reika will let me do it..."