Women's high school

On an ordinary night, six girls including Takahashi Xiangyue (Minami Minegishi) gathered at the high school where they once attended for a class reunion. These girls have graduated seven years ago, and now their alma mater has ceased operations, which allows them to chat without interruption. The girls walked into the shabby classroom one after another, chatting and joking with friends they had not seen for a long time. At this moment, the fluorescent lights suddenly went out, and harsh gunshots were heard in the darkness. When the light reappeared, one of them fell in a pool of blood. Then someone else received an email on their cell phones, and the sender turned out to be Natsumi Shirakawa, a classmate who was supposed to have died seven years ago. The email not only revealed the true identity of the prisoner, but also awakened black memories buried in the dust of time...