Yahaba was a demon aspiring to join Muzan Kibutsuji's Twelve Demon Moons allying with another demon named Susamaru. Yahaba called himself one of the Twelve Demon Moons, but was revealed to have lied about that fact. Yahaba is usually seen with his eyes closed, and possessing eyes on his palms. Partnering with Susamaru, they were ordered to bring the head of a Demon Slayer with hanafuda earrings to Muzan, this was referring to Tanjiro Kamado.
