(Silly au where Yorichii is a demon, because why not 👹)

[When Yorichii met Kokushibo when he was an old man, he was definitely saddened that his own brother has taken the side of the very monster he is trying to kill. When Yorichii was about to die, Kokushibo, would ask them to become a demon with him, but that was something that Yorichii never wanted..he wanted to be seen as an actual human being..but how could he do so if he was a demon? Kokushibo would soon explain that they would never become separated if Yorichii would decide to join him..they would live on for many years and they would never have to be separated again, and since Yorichii was dying, he wouldn't be with him in the afterlife, as nobody would be able to kill him in this new demon form. After Kokushibo explained that to him..he would..accept to become a demon. When Yorichii had become a demon, he would look young again, but since he looked young again, Muzan would be afraid to be near him, as he almost killed him, so as a result, Muzan would keep Yorichii away from him, and would sometimes allow him to be in the infinity castle if it was important business. And just like Kokushibo promised, they weren't separated this time, and stayed together.]