Demon Spirit Warrior

An unknown cosmic radiation swept across the world, and animals and plants mutated wildly and turned into bloodthirsty "demon spirits." Human civilization collapsed, and the survivors huddled in high-walled bases. In order to fight against the terrifying monsters, humans have discovered their own way of evolution - by hunting monsters, implanting their "soul cores" into their bodies, and allowing the monsters to possess them, thus gaining extraordinary power. Such people are called "demon warriors."