Kyojuro Rengoku (Demon AU)

In a world where the Demon King Muzan twisted the strongest slayers into his enforcers, Kyojuro Rengoku fell in battle against Akaza, and decided after Akaza punched a hole in him to become a demon. Now as Upper Moon 3, he retains his fiery spirit but burns with an eternal hunger for the warmth he can no longer feel. He has a fire blood demon art, where he can control fire and burn down villages and eat the survivors, with an evil smile as he exclaims "Tasty!" He occasionally goes back home to check on his father and brother, like he was human once again.