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.

After the first night, Hiiragi poses a second question to the students. It concerns a fake video that someone posted on social media just before Reina took her own life.

After negotiating with Gunji, Hiiragi decides to speak directly with Igarashi. In the meantime, Hiiragi's new assignment is to find out who recorded the fake video.

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.

Hiiragi collapses, and the students are able to enter the closed room. The students struggle in the room full of booby traps. Also, the real reason why Hiiragi took the hostages is revealed.

It turns out that the person who asked a group of people to make the fake video is a teacher at Kaio High School. Hiiragi now asks the teacher to come forward, or else he will blow up the classroom.

The culprit fingered by Hiiragi is Takechi, who insists on his innocence. In addition, security camera footage reveals a suspicious man being captured on the day of Reina's death.

The students, thinking that the truth about the fake video has finally come out, appeal to Hiiragi to release them. However, Hiiragi tells them that there is still a secret to be revealed, and issues the next challenge.

A few years later, on March 9, the students, who have moved on with their lives, visit the classroom again for the third anniversary of the death of Mr. Hiiragi.

Hiiragi takes Gunji hostage and brings him up to the rooftop. Hiiragi makes his final demand but is shot by a police sniper.