I, Kuuya Aoki, woke up in a locked classroom. Other than me, the delinquent Yamagishi, Kawano the "Queen" of female students, the popular Tajihi who has a strong sense of justice and the rest of my classmates were gathered here.

The one who did this act was Ayano Koga, the older sister of Yuuno Koga, who committed suicide a month ago. She attached explosive collars on our necks to force us to participate in a death game.

Students dying due to selfish reasons. Sacrifices born out of indifference. Inflicting pain. It was the very picture of bullying itself.

Amidst people dying one by one, I knew her objective. It was not only revenge…