This was a special containment 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 appeared in the Netherworld, stood facing these nine demon teachers.

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

Then, the sound of the containment room door opening echoes as someone enters.