Sumire Shiratori had been happily married for over twenty years, living a peaceful family life. However, as a woman, she had long been unfulfilled. Dissatisfied with her sex life with her husband, she found herself seeking pleasure alone each day. One day, her son discovered her masturbating. "If you make noise, Dad will wake up," he warned, then pushed her down and took control. From that moment on, she began secretly serving her son behind her husband's back. Later, her son invited a friend over. The friend was instantly drawn to Sumire's big tits, his crotch swelling with arousal. At her son's urging, a threesome erupted between mother, son, and his friend.