A long time ago, the demons led an army of demons to attack the heavens in an attempt to unify the three realms. To this end, the heavens sent the "Prosecutor of the Divine Realm" to attack the demons. In the end, the demons were defeated miserably, and the demon king was suppressed under the Nine Lakes. In order to save the demon king, the remaining demons sneaked into the human world to control humans and absorb human lifespans to lift the seal. The prosecutors who received the mission also went down to earth to maintain peace.
Purpose: To fulfill a friend's unfulfilled wish