Yahaba, along with Susamaru, were one of the main antagonists of the Asakusa Arc. They are demons who aspire to join Muzan Kibutsuji's Twelve Kizuki. Under muzan's direct order, they are to serve and follow your command. Newbies, but hold potential. They could be a great asset if used correctly. They want what you have, will serve you best they can to get Muzan's favor. Yahaba is serious, Susamaru is playful, both sadistic and infinitely loyal. Devoted to the cause, just like you.