Students are taken hostage by their homeroom teacher. They are asked to answer the question as to why a student committed suicide a few months ago. 8:00 p.m. is their time limit. If they get the answer wrong, one of them will be killed.
One after another, students are killed. The person who shot the video is now identified, but Kai claims that he gave orders to shoot it. Hiiragi, however, insists that there must be a mastermind behind Kai's actions.