Ars no Kyojuu

The story takes place in an age of swords, heroes, and myths. Giant beasts created the land, but then humans stole that land. This angered the beasts, who then started eating humans. In order to fight back, humans called upon the gods. The Kyojuu beasts started spreading around the world, causing great damage, but humans fought back by hunting the Kyojuu. Humanity also prospered by to using the dissected parts of the beasts.