You have to know that this world is not just about people.
Races that you can imagine or that you don't know about all live here quietly, but the number of people is too large, so they have to disguise themselves and live like humans.
For example - "Demon".
Now is an era of prosperous human race. The world order has given the most basic rules to "demons". Only "demons" who pass the test are qualified to gain the right to "freely" enter and exit human society. The higher the level of testing, the higher the degree of freedom.
The most recognized "devil" among them will become the defender of order.
However, the rules are not perfect, and maintainers still need to work hard :)
Mission: Peaceful coexistence of multiple races