Jun always looked forward to visiting his in-laws, especially to spend time with his wife's mother, Ryouko. One could say his main purpose was to secretly admire her plump ass and the trembling cleavage that seemed to beckon men. Today, as usual, he was sneaking peeks at Ryouko, eager for his usual thrill—until he accidentally discovered her on the phone with her secret lover. Overcome by loneliness from not being able to meet him, she began masturbating without realizing she was being watched. Witnessing her intimate act up close, Jun's feelings quickly evolved from mere voyeurism into something far deeper.