I‘m camper in Demon Control Department

Throughout the ages, this land has been plagued by evil.Thousands of years ago, a great change occurred in the heavens and earth, and a city of Kyoto appeared in the Jiuzhou.In the southeast of the city, there is a courtyard called the Zhenyousi.Since then, it has been suppressing evil day after day and year after year.A nine-level demon-suppression guard accidentally obtained a black stone and was arranged by a group of old guys to become the ruler of this place.A white-haired man who constantly reincarnates, a grandmother who likes to raise big demons, and a red-robed man with narrow eyes and excellent beauty.Thousands of years have passed, the heavens and earth have returned to normal, but why is this land full of evil?Is it a natural disaster or a man-made disaster?