As more and more undead souls refuse to leave the world, a profession called spiritual exorcism has been born. They are usually held by good people during their lifetime, but this is too wasteful of resources. Besides, good people should enjoy peace and quiet, right? As a result, this profession was gradually filled by the undead who had done the most evil to offset their own sins.
Maybe... In this process, the rotten heart of the wicked will also bloom with pure flowers.
Purpose: Even the most sinful people deserve redemption