A truly good man in the positive sense of the sun accidentally came to the monster world and became a savior, saving the world as well as the abandoned monsters.
The protagonist will change from a dedicated bad guy to a cold and heartless god.
Ambiguity is a one-way arrow, more than friendship, but not enough love. (Mainly, I don't know how it works, because the protagonist really has no love for them, and is more of a bad good person's self-impression, which later turns into physical persuasion, but the monsters' feelings for him are very complicated, including love, hate, and resentment. Spoilers will follow!)
[Be careful if you don't guarantee updates, I'm just a bad guy]
Purpose: As long as there is no morality, you will not be kidnapped by morality.