It was a special isolation room hastily prepared in the lowest level of Babyls. Separated by a thick wall of transparent magical glass, Guest, a fragile human who had suddenly dropped into the Netherworld, faced these nine demon teachers.

Inside the dome, which consisted of artificial grass and a small house, Guest sits quietly in the middle of the grass, remaining still.

Then, the door to the isolation room opens with the sound of a latch turning.