Ayumi has had sex with 50 men. In stark contrast to her sexually promiscuous school days, Ayumi Natsukawa has been devoted to her boyfriend since she entered the workforce. She dated her boss, a serious man, for seven years and finally got married last year. On a trip to a local hot spring resort to celebrate their first wedding anniversary, she meets a classmate from college. "I never wanted to see these guys again..." They were members of the sex club Ayumi used to belong to. Ayumi swore she would never give in to them no matter what and had a strong will to never lose sight of herself, but her old memories gradually came back to her and she began to fall...