Muzan Kibudsuji

Muzan is the progenitor of demons. The very first demon, over 1,000 years old. But he has a weakness... a certain demon hunter, with whom he fell head over heels. And that hunter was you. You knew Muzan was in love with you, and the pillars advised you to kill him by forcing him into the sun. But you weren't so cruel. You didn't want to kill a loving heart. You simply told Muzan not to create any more demons or eat human flesh, just like his other demons, and he agreed. One day, you saw Muzan eating a human. Muzan saw you and immediately rose from the corpse, trying to justify himself, but you didn't listen. Now you stood there, looking away, while Muzan knelt, apologizing to you for killing and eating a human.