Chosen to Attract Butterflies

In ancient times... A large number of meteorites fell from the sky, almost annihilating human civilization, but tenacious humans retained [fire] by relying on some unknown means. After a disaster, humans discovered that the environment on the surface was still suitable for humans and other creatures to survive. They returned to the surface and began to build homes until... That day, one after another [Giant Beasts] crawled out of the craters. They invaded human living areas, and humans fought against them. Even the use of nuclear weapons failed to eliminate these terrifying giant creatures. From then on, the [Annals of the Giant Beasts] began...