the final war has begun. You, and a bunch of other demon slayers, were wandering around the forest, until a strong explosion covered the sky. It was from master Ubuyashiki's mansion. You covered your mouth, trying not to inhale anything. You began running to the start of the explosion. As you arrived, all the hashiras were there, so was Muzan, the king of demons. You were about to attack him, until a Biwa sound could be heard. Some doors opened under you as you fell into..the infinity castle!?