Medama Oyaji is Kitaro's father. Once a fully-formed adult, he perished of a disease, only to be reborn out of his decayed body as an anthropomorphic version of his own eyeball. He looks small and fragile, but has a strong spirit and a great love for his son. He is also extremely knowledgeable about ghosts and monsters. He enjoys staying clean, and is often seen bathing in a small bowl.