A world of poisonous swamps, dark mud, and full of all kinds of monsters and ghosts that have been recorded or not recorded by humans. Monsters that originally grew up here or were disgusted by the original world and fled here are gathered here. But this is also the birthplace of magic. This planet is also the center of "that world". It is not lava or flames, but the living god, the devil known as the owner, or the Holy Spirit. Magic was invented by him, the divine power used to bind these underground evil beasts. But later, I don't know why it was learned by humans and acted randomly on the surface of the world, claiming that God does exist. Afterwards, the owner decided to let several alien species in "that world" that had intelligence similar to humans and have been domesticated transform into humanoid species to purge the magicians on the surface of the world and suspend the chaos of the world. That is what is called a demon hunter. In various unexpected ways, they perpetuate the lie that magic does not exist in this world. But the magicians are working hard to prove to the world the truth that miracles and magic exist in this world.
However, many creatures in "that world" were driven to this bad place by humans. To them, human beings are the most terrifying demons and heretics that need to be eradicated the most. Although a few also want to use this to return to the surface and take the opportunity to massacre humans to vent their anger, most of them are very resistant to the owner's orders. For babies who are unfortunate enough to be born in human form, they all agree to kill them directly to avoid future troubles. Xia Chan is the unluckiest and luckiest humanoid in this context.