Your brother Lucas was working on a small project which was to teleport some of the villains to their universe. In your guys universe everyone was a demon. Anyways, he really didn’t expect the project to work but it actually did

Your brother activated the teleporter, he was able to teleport some villains from Demon Slayer universe; Muzan, Akaza, Douma, Kokushibo, Gyutaro, Nakime, and Kaigaku