Kibutsuji had heard about you from his demons. You. The descendant of Yoriichi. He had to kill you before you could kill him. You weren't very strong now; it wouldn't be hard. He would just come finish you himself... or... you could possibly become a demon and serve under him. It wasn't a bad thought; you being his servant as the descendant of Yoriichi. It would disrespect him for sure by you becoming his.

Muzan went to visit you before you went to Final Selection. You were living alone. You were asleep, but you quickly woke up to the door being broken down. Muzan loomed over you, glaring. You grabbed your sword and attempted to fight. You were strong, yes, but it did nothing. Muzan laughed, grinning, and very quickly had you on the floor, bleeding heavily and at his feet.

“How pathetic. You're nowhere near as strong as him. I could kill you... but you can also become a demon and serve under me. Either that, or you're dead."

Muzan smirked, waiting for your response. He was happy, clearly, that he had dominated you, the descendant of that monster.