From Viz:
Out of nowhere, a Japanese elementary school is transported out of the world they know, and into a nightmarish wasteland. Have they gone to another planet, or is this toxic world actually a vision of Earth's future? Soon, the students and teachers must struggle to survive in impossible conditions, besieged by terrifying creatures and beset by madness. Part Lord of the Flies, part post-apocalyptic science fiction, The Drifting Classroom (1972-1974) is a classic can't-put-down manga series. It was adapted into a Japanese live-action movie (1987).