Mikoshi-nyūdō (Japanese: 見越し入道), also known as Mikoshi (Japanese: 見越) or Miage-nyūdō (Japanese: 見上入道), is a mythical creature (yōkai) found in Japanese folklore, especially common in tales from the islands of Sikoku and Kiusiu and the northern reaches of Honsiu.
Mikoshi-nyūdō usually appeared at night to lonely wanderers at crossroads, by stone bridges, and on empty streets and roads.
The creature had a bald head, was tall, and would sneak up from behind, bend over, and peek curiously over the shoulder. At first it was not large, but with every moment that the man looked at it, it grew to enormous size.
At some point it would crush the victim, causing his death. It was believed that the land on the side on which the monster fell would be plagued by various cataclysms.
An account of an encounter with Mikoshi-nyūdō entitled Mikoshi-nyūdō o miru koto (On Meeting Mikoshi-nyūdō) is found in Tonoigusa:
A samurai, when he was young, went hunting with his dog. However, he had no luck. When he got about one away from home, he decided to go back, but before setting out he decided to rest on the top of a mountain and then he noticed something small that was getting bigger by the moment.
Then he realized that what had emerged from the darkness must be a monster which, illuminated by the light of the stars, looked like a Buddhist monk. It was Mikoshi-nyūdō, a monster into which old tanuki and other amazing beings could transform.
While the monster was getting bigger and bigger, the samurai drew his bow and aimed at it, but he did not know where to aim the arrow. At one point, the monster disappeared along with the stars and everything around it.
An impenetrable darkness enveloped everything and the warrior could not find his way back. However, he was a clever man and summoned his dog, which had accompanied him on his hunt.
He tied one end of the blindfold to the dog's collar and the other end to his own belt, and in this way the guide reached a house. When he saw the glow emanating from it, the darkness disappeared, and the warrior saw that he was standing at the door of his own house.
From that time on the samurai never set out on a journey alone.
In the story given, the author mentions that the monster could have been a tanuki or other magical creature.
Although other creatures also possessed such power such events were commonly attributed to Mikoshi-nyūdō. He was often called an aristocrat or chief chief of monsters.
During his appearance one could hear the rustling of bamboo leaves, which was explained by the fact that the monster was sticking its head on them.
In order to protect oneself from being crushed by Mikoshi-nyūdō one should shout when seeing him: "Mikoshi-nyūdō, I see you!" and lay down with one's belly to the ground, and then the monster would melt into the air.
The other known way of defense was to watch it, but starting from the head and going towards the feet, then the monster would shrink instead of growing.