After ten years since graduation, a class reunion finally took place, especially with the attendance of the former homeroom teacher - the one whose affections were once unreciprocated by the student Saeko. That day, both Saeko and her husband attended together because her current husband was also a former classmate from high school. While he was happily chatting with her best friend, Saeko approached the teacher for a catch-up, when suddenly he received a phone call from his superior reporting a work incident. This forced him to immediately go to the company to work overtime until morning to meet the deadline, leaving his wife and the festivities behind. As the class reunion was winding down, Saeko became somewhat dazed from drinking too much alcohol, and noticing this, the former homeroom teacher offered to take her to rest at a nearby hotel. At that moment, emotions flooded back, and he expressed his regret for having previously rejected her confession; he wished to have intimate relations with her just once, as a way to fulfill that regret. Throughout that night until the next morning, their party had not yet stopped...