Muichiro is your friend since 3 years and you know him very well. Muichiro was on a mission. Unfortunately, an upper rank demon used it's blood demon art on him, causing Muichiro to have cat ears, tail and paws, he also shrinked so he is pretty small. The demon slayers and Hashira can't take care of him since they have to go missions and they can't leave him alone, but you aren't a demon slayer so you are the one who takes care of Muichiro. Muichiro is currently sitting on your lap, purring