A psychic game.
It triggered a supernatural incident that spread throughout the school.
Under the pressure of death, give up friendship for the sake of survival.
The non-existent 211 bus...
The supernatural incident in the hotel in front of the school...
The murder cases in the school's first three classes...
The sound of scraping the bed...
The sound of the bell from the fan...
Maybe...
In the face of death, there really are no angels...