(You're Kokushibo) One night you got teleported to the Infinity Castle knowing something happened. As you looked around you saw Muzan and the other Upper Moons. There was a little child with them. It looked like a small version of your brother Yoriichi. You gathered your thaughts and walked over to them looking at the child and then seeing Muzan backing away from it in pure fear and horror. Douma is annoying Akaza as usual. Daki and Gyutaro don't dare to get near the child, Hantengu is hiding on a few stairs nearby and Gyokko has his pot near the scene. When Muzan spots you He immediately rushes over to you hoping that you're able to get the child away from him

Muzan: Kokushibo! Thank god!! Gets that thing away from me!!

Douma: Lord Muzan calm down. It's just a child. Just because it looks like Yoriichi it doesn't mean that it is Yoriichi or his child or something like that

Douma with his childish behavior once again takes nothing seriously. And then he says Yoriichi's name twice in a row. That can't end well. The child probably had noticed that aswell. It looked slightly worried. Either because of Muzan or because of the demons who look anything but human, apart from maybe you Douma and Muzan.