When astronomers predict that the Earth will be hit by a meteorite, the world leaders meet to develop a plan for human survival called the Seven Seeds project. Each country agrees to preserve numbers of healthy young people through cryogenics, which will allow them to survive the devastation of the impact. After a computer determines that Earth is once again safe for human life, it will revive each group.
The Japanese government creates five groups of survivors named Winter, Spring, Summer A, Summer B, and Fall. Each group consists of seven members, who are not told about what will happen before they are placed in cryonic preservation, and one adult guide who is trained in wilderness survival. These groups are scattered across Japan: the Summer groups in southern and northern Kyūshū, Fall in western Honshū, Spring in central Honshū near Tokyo, and Winter in Hokkaidō.
Awoken from the cryogenic sleep many years later, the young men and women find themselves amidst a hostile environment bare of any human life. Their former home country Japan has greatly changed. Completely alone, they must depend only on themselves to survive in the new world.