Miage Nyūdō is a mountain yōkai who appears as a recurring antagonist in the anime and manga series GeGeGe no Kitarō. In the series, he is depicted as a large, humanoid figure resembling a bald monk or priest, often with a single large eye, drawing from the traditional folkloric creature known as miage-nyūdō from Sado Island, Niigata Prefecture. His motivations center on the inability of yōkai to reproduce; he kidnaps humans—especially children—who venture near his mountain, with the intention of training them into new yōkai. He uses his wind-based abilities to capture his victims, and in many incarnations he operates a school for turning mortals into yōkai. His personality is that of a determined and sometimes cruel creature, but he is not without a sense of purpose: he sees his actions as necessary for the survival of yōkai kind. He is also notably territorial and will retaliate aggressively if his home is disturbed.

In the story, Miage Nyūdō often serves as an early or significant opponent for Kitarō. He appears across multiple anime adaptations, including the 1968, 1971, 1985, 1996, 2007, and 2018 series, as well as in the original manga chapter of the same name. His role frequently involves a confrontation with Kitarō, who must rescue the captives and stop his scheme. Key relationships include his conflicts with Kitarō and his allies such as Neko Musume, as well as occasional cooperation with other antagonistic yōkai. In some series, he is allied with or manipulated by other villains like Nanashi.

Miage Nyūdō possesses several notable abilities. He can control and manipulate air, using it to create powerful winds, blast enemies, or inhale objects and people. He can also change his size at will by consuming air, becoming enormous to intimidate or crush opponents. His most devastating technique is “Reikai Nagashi” (Spirit World Sending), which transports victims to the spirit world, effectively removing them from existence. However, all his abilities rely on his breath, making his throat a critical weak point—if it is blocked or compressed, he loses his power. Another vulnerability is the traditional chant “Miage Nyūdō, mikoshita” (I have seen past you), which, when spoken by an opponent who shows no fear, can nullify his strength and cause him to vanish. Over the course of the series, he does not undergo major character development; he remains a standard yōkai antagonist whose appearances are episodic, although his portrayal can vary from a comedic villain to a more menacing threat depending on the adaptation. His design consistently incorporates elements of the folkloric aobōzu, though the two are unrelated in origin.