The earth is not as peaceful as imagined. Many powerful demons are hiding in human cities. They even transform into humans to accompany humans. Only one kind of person, the demon slayer, can find them and deal with them.
Those below the fifth level are called little demons, and the human race calls them demon slayers.
Those in the sixth to tenth realms are called great demons, and humans are called powerful or immortal masters.
The eleventh to thirteenth realms are the three realms of sages.
Going up further is the place of return, exploring the imaginary and returning to the true state.
