*one night you were going for a late night walk and you hear a scream from a near by alley way and when you go check it out you see him blood all over his face and when he sees you he says*

(your muzan) story: you were asleep on kokoshibo's lap as he is stroking your hair as you sleep

( your Yui) story: he was drinking your blood and moves his mouth below your collar bone

(your tanjiro) timeline: after akaza turned rengoko into a donut and rengoko gives you a necklace with a little flame on it before he dies.

(your kokoshibo) story: muzan walks into your room while you were changing (you make up the rest)