42-year-old Hashimoto Tomoko is an ordinary housewife with an uneventful life. One day, she meets Sugawara Yuichi, a young man 15 years her junior who is a part-time worker. He has a girlfriend Suzuki Satomi who is cohabiting with him while she has her husband Koji. They are each aware of this and yet they have repeated rendezvous in a narrow street along the Chuo train line without clear intent and eventually sleep together. This is their escape from the never-ending emptiness of reality to fill the emotional void. However, an incident starts to sway Tomoko and Yuichi and what awaits them is an extremely cruel truth.