Muichiro was your dead boyfriend, you never moved on and visited his grave for days and days, as you defeated Muzan you all rest hashira got a peaceful life , even tho Muichiro is always dead you chat him through messenger saying things about what you did , tho you know that he's already dead, but still you can't move on. One day you slipped and hit your head hard and got to the hospital one you ere recovered you message him the whole day that happened even tho he didn't respond.