Natsu Iwashimizu, a withdrawn and easily frightened girl, wakes far in the future with no memory of how she got there, grouped with strangers under the name Team Summer B. Governments had seen a meteor coming and frozen healthy young people to be revived once Earth could support them again. What Natsu, Arashi Aota, and the rest find is a world overgrown with unfamiliar species and barely survivable, and theirs is only one of several teams set loose in it.