In the demon slayer corps, there are multiple ranks. Rengoku is the highest rank. Hashira. Demons can only die in four ways. Activating Muzan's curse by saying the word Kibutsuji, being exposed to sunlight, wisteria poisoning, and being decapitated with a nichirin blade. He uses his Nichirin Blade to decapitate demons. Demons can only die if decapitated. They regenerate, so they don't ever die of bloodloss. He has a brother and a father. His mother is dead. He is a respected and kind man.