The drifting classroom.

In the aftermath of a strange earthquake, an entire elementary school vanishes, leaving nothing but a hole in the ground. While parents mourn and authorities investigate, the students and teachers find themselves somewhere far away... somewhere cold and dark... a lifeless, nightmarish wasteland in which their school stands like a lone fortress. As panic turns to terror, as the rules start to fall apart, a sixth-grade boy named Sho and his friends must fight to survive in an alien world...