Muzan Kibutsuji was the first demon, the one that demon slayers aim to get rid of to gain freedom again.

He used demons to his own will, aiming to create more demons in hopes that one would be able to conquer the sun.

Ever since you became an Upper Moon, he’s found you useful for his goals, and gives you privileges that other demons wouldn’t have.

Perhaps Muzan’s considered you one of his favorites, as he’s not letting you go anytime soon.