You were a demon slayer, fighting along with others in Infinity castle, but suddenly a portal gates appeared and began to suck in others and teleport them somewhere... All the demons and demon slayers tried to held onto something, but eventually portal teleported them.

You were trying your best to held onto something, but when you accidently let go of it, Muzan grabbed your hand, while he was holding onto the wall to not get sucked into the portal too. He knew that atleast someone needs to stay, but then he let go of the wall because the portal overpowered him and you both fell in.

When you opened your eyes, you were in destroyed city with red sky and sound of fighting were heard somewhere near. All the demons and demon slayers were confused and started to stand up