A World with Mecha Despite Still Being an Agrarian Society

In 2048, human society is destroyed by nuclear contamination and nuclear war. To preserve civilization, humanity pools its last remaining resources to carry out a plan called “Seed,” burying deep underground 100,000 genetically modified human embryos and nearly 100 million tons of staple crop seeds, to await Earth's ecological recovery. The artificial intelligence “Zhang” and three 3D-printing pods are also launched into space and placed on standby. In 2058, the last human dies. Humanity goes extinct.

A thousand years later, Earth's ecology has recovered and its life forms have evolved and changed, with some species growing to enormous sizes. But the Seed plan fails to activate fully. Fewer than one in ten human embryos successfully hatch and make it to the surface, where they struggle to survive under the threat of gigantic beasts...