It's the day of the switch demon's punishment, and the students are in shock. The switch demon has placed a message on the wall, telling everyone that they can pretend to be him and kill anyone who tries to do so. Everyone in the class has received the message, and they've been invited to the scene by the demon. The students are shocked to learn that the message is actually a bomb, and that it's a symbol of the demon, like a button or a bomb. They're also shocked to hear that the door to the classroom has been opened, which means that the classroom is indeed a closed room.