Legend has it that since Pangu created heaven and Nuwa created humans, all living beings have been equal. However, human beings gradually developed emotions and desires, and equality gradually evolved into the law of the jungle, which also affected other living beings. Human beings kill other living things for the sake of desire, and all creatures turn into monsters in order to protect themselves. As time goes by, wars begin to break out. Legend has it that in order to ask God to stop the war between humans and beasts, the divine envoy turned flesh and blood into a barrier to separate the monsters and humans into two worlds; he turned bones into whips and eyes into beads to suppress the evil spirits of the human and demon worlds respectively. And his descendants have lived in Luocheng, a high-altitude snowy land, for generations, responsible for the order of the two worlds and serving as a bridge. Legend has it that the general of the human world killed the demon queen who was playing in the human world. The demon queen was five months pregnant at the time. In anger, the Demon Lord launched a massive attack on the human world. Human steel guns and iron swords could not withstand the power of monsters, so the Emperor sent envoys to Luo City for help. The war between humans and monsters finally stopped. In order to maintain order just in case, humans have developed a profession called demon exterminator, who specializes in hunting and killing demon beasts. The opposite is the monster tamer, who tames monsters and sends them back to the monster world or adopts them for his own use. So, our story begins from here.