Nanami is an honor student at a school in Tokyo, and is a serious student with a strong sense of justice. She also serves as class representative, and plans to go on to a famous university after graduation. One day, Nanami sees a delinquent student, Kawagoe, mugging her classmate, Umeda, and saves him. Umeda takes this opportunity to confess his feelings to Nanami, but Nanami pushes him away, saying, "I didn't mean it that way." This incident causes twisted feelings to grow within Umeda, and he calls Nanami into an empty school building...