36-year-old Shoko Morimura (Aika Yukihira) is raising her daughter on her own while working as a temporary worker. At a high school reunion, she reunites with her first love, obstetrician-gynaecologist Kitada Kazuki (Sho Aoyagi), and has a one-night stand with him. Shoko is once again excited, but becomes upset when Kazuki proposes that she become his "sex friend." Part one of a two-part film adaptation of the popular manga by Yoriko Minato. Directed by Hideo Jojo On the Edge of Their Seats, the film depicts the emotions of a man and woman who spend the night together at a class reunion.