Sonoko remarried and now lives with her husband and his son, Yoshio, but she suffers from intense sexual frustration due to a completely nonexistent sex life with her husband. One day, she is seduced by Yoshio and forcefully seduced against her will. Though Sonoko knows what they're doing is wrong, her body instinctively gives in. Yoshio's demands gradually escalate, forcing her to seek pleasure at night while her husband sleeps nearby. Soon, she becomes an outlet for Yoshio's friends' sexual desires, and Sonoko is drawn deeper and deeper into a world of submission.