Yagyou-san

Also Known As: 夜行さん; also Yagyō-san, Yagyō-sama, or simply Yagyō. From yagyō, “going by night” or “night procession”, the same word as in hyakki yagyō, the night march of a hundred demons
Region/Culture: East Asia
Mythos: Japanese Mythology
Primary Type/Nature: Demons and Devils
Mythical Attributes: A one-eyed oni who travels the roads of Awa on a fixed set of calendar nights, mounted on a decapitated horse.
Role in Mythos: He is the reason certain nights of the old Japanese year were nights nobody went outside.
Relation to Humans: Anyone who meets him on the road is thrown down or kicked to death by his horse, so households in Tokushima kept indoors on his nights and taught their children which nights those were. A person caught out in the open could still survive by laying a straw sandal on their head and pressing themselves flat to the ground until he had passed.

The road is empty on the night before spring begins, and it stays empty because everyone in the valley knows what uses it. Frost has hardened the ruts. Somewhere below the treeline a horse is coming up the track at a working trot, four hooves striking cold ground in a rhythm that carries much further than it should, and the sound is wrong in a way that takes a moment to place. There is no snorting. No breath. The animal has no head to breathe with.

The rider is Yagyou-san, and in the mountain villages of Awa, the old province that is now Tokushima, he was as real as the weather. He was described as an oni, bearded, with one great eye set in his face, and he sat astride a kubikire-uma, a horse cut off at the neck. He did not hunt. He did not knock. He simply came along the road on the nights that belonged to him, and whoever happened to be standing on that road was thrown aside or trampled under the hooves of an animal that could not see them because it had nothing left to see with.

What made him frightening was that his nights were published. They were not a matter of luck. New Year’s Eve was one. Setsubun, the eve of spring, was another. The Kōshin vigil nights counted. Beyond those came the yagyō-bi, the night-procession days, a taboo inherited from Onmyōdō and set out in the medieval encyclopedia Shūgaishō, which fixed one forbidden day in each month by the animal signs of the old calendar. Different tellings recite the sequence slightly differently, which is what happens to a calendar passed down orally for centuries, but the principle never wavered. On those dates the roads belonged to the hundred demons, and Yagyou-san was the one who came down yours.

He did not always stay outside, either. In the Yamashirodani district of Miyoshi, families said that if you sat in your own house on one of his nights and talked about what you were having for dinner, a hairy hand would come in from somewhere and reach out toward the food. The story stops there. It does not explain the hand, or say what happened next, or connect the arm to a body. That restraint is the most convincing thing about it.

Beyond the beard and the single eye, almost nothing was preserved about how he looked, and the record is honest about the gap. What was preserved instead, in obsessive detail, was the horse: headless, sometimes running the roads entirely alone, and in some districts more famous than its rider. Along the lower Yoshino River and eastward into Kagawa, the horse itself was called Yagyou-san. There the name belonged to the animal, it came on Setsubun night, and nobody expected anyone to be sitting on it. The tradition of the headless horse without a rider is in fact the more widespread of the two, which raises the awkward possibility that the oni was attached to it later.

Across the mountains in Kōchi, near Tokoroyama in Ochi, they said Yagyō came along the night paths shaking a shakujō, the ringed staff a travelling monk carries. Its rings would sound in the dark, closer and then past. No one there had anything to say about what he looked like. He was a noise on a mountain road, which in a place of that kind is quite enough.

The written trail begins in 1922, in a small folklore journal called Tsuchi no Suzu, where the Awa belief was set down with its calendar and its remedy intact. Yanagita Kunio picked the entry up for his catalogue of yōkai names in 1939 and it entered the national record from there, later joined by field notes gathered from Miyoshi in 1937 and from Kōchi in 1942. The name also surfaces far away in Hachiōji, west of Tokyo, attached to something else entirely: a princess fleeing the fall of Takatsuki Castle whose horse was beheaded beneath her, ran on regardless, and rose into the sky. She and the headless animal are said to wander on nights of the full moon, and to see them is to be ruined. Same words, different creature.

His powers are borrowed rather than owned. He does not curse, transform, bargain or speak. His entire strength is the calendar, which puts him on a specific road on a specific night with a large animal underneath him, and the momentum does the rest. He kills people who are simply out walking.

The limits are equally plain, and they are the reason the belief could be lived with. He keeps to the road and to his dates, so a household that stayed indoors was never in danger. He passes through rather than pursuing. And if the worst happened, if the hooves came up the track while you were still out in the open, there was a countermeasure everyone knew: take off a straw sandal, set it on top of your head, and lie face down in the dirt. Cheek in the cold grit, straw pressing on your hair, the sound growing and cresting and going away down the valley. Then he was gone, and you got up, and you went home.

Frequently Asked Questions

Who is Yagyou-san?

Yagyou-san is a yōkai from Awa Province, now Tokushima Prefecture in Japan, described as a bearded oni with a single large eye who rides a headless horse. He appears on a fixed set of calendar nights and kills anyone he meets on the road.

When does Yagyou-san appear?

Yagyou-san rides on New Year’s Eve, on Setsubun, on the nights of the Kōshin vigil, and on the yagyō-bi, the night-procession days listed in the medieval encyclopedia Shūgaishō. These were taboo days inherited from Onmyōdō, with one forbidden day fixed in each month of the old calendar.

How do you survive meeting Yagyou-san?

The traditional remedy is to place a straw sandal on your head and lie face down on the ground until he has passed. Yagyou-san does not hunt or pursue; he travels the road, so a person flattened beside it is left alone.

What is the horse Yagyou-san rides?

It is a kubikire-uma, a horse severed at the neck, which runs without a head. In the lower Yoshino River area and eastern Kagawa the headless horse is itself called Yagyou-san and appears on Setsubun night without any rider, and traditions of the riderless horse are more common than those of the pair.

Is Yagyou-san the same as the Yagyou-san of Hachiōji?

No. In Hachiōji, west of Tokyo, the name attaches to a princess who fled the fall of Takatsuki Castle on a horse that was beheaded beneath her and kept running. She is seen on full-moon nights and is regarded as a separate tradition that happens to share the name.