Minamoto no Yorimitsu / Raikō

Minamoto no Yorimitsu — usually called Raikō, which is the same name read the Chinese way — lived from 948 to 1021 and was entirely real. Governor of Izu and Kōzuke. Landholder in Settsu. A servant of the Fujiwara regents, which in practice meant a working aristocrat with troops.

In folklore he is something much more specific.

He is the office you called when the problem was supernatural.

He had a squad, and they all have their own legends

Raikō's four retainers are the Shitennō — the "Four Heavenly Kings," a name borrowed straight from the Buddhist guardian deities who stand at the corners of temple halls with demons pinned under their boots.

The borrowing is not subtle and was not meant to be.

Watanabe no Tsuna — the swordsman who cut the arm off a demon at the Rashōmon gate and took it home in a box, and who fought the woman at Uji Bridge who had turned herself into a demon out of jealousy. His descendants are, by tradition, still exempt from throwing beans at demons at the winter festival — because the demons already know that family and stay away.

Sakata no Kintoki — better known as Kintarō, the golden boy raised in the mountains by a mountain-witch, who wrestled bears as a child. Every Japanese person knows him from picture books. He grew up and got a job with Raikō.

Urabe no Suetake — the one who took the dare. There was a bet about whether anyone would walk out at night to the place where the ghost of a woman who died in childbirth was said to hand her baby to passers-by. He went. He came back.

Usui Sadamitsu — the fourth chair, with the thinnest file of the four. Somebody always ends up being the fourth.

The famous cases

Shuten-dōji. The demon king holding Mount Ōe, stealing the daughters of the capital. Raikō's team went up disguised as travelling priests, brought a gift of sake that was poisoned, drank with him all evening, waited for him to pass out, and beheaded him in his sleep.

Not a duel. An operation.

The tsuchigumo. The giant earth-spider. Raikō was ill in bed when it came for him — appearing as a priest, then as a monstrous shape, tangling him in thread. He cut at it from the bed, followed the blood trail out into the hills, and finished it in its burrow.

That's the image Kuniyoshi painted and everybody has seen: the sick man on the mattress, the retainers playing a board game and not noticing, and the enormous spider filling the whole top of the picture.

Now here is the part that genuinely has no parallel anywhere

The swords exist.

Not the demon. The weapons.

Dōjigiri — "Demon-Child Cutter," the blade that took Shuten-dōji's head — is a real sword. It is a designated National Treasure of Japan. You can look at it in the Tokyo National Museum.

Onikirimaru — "Demon Cutter" — likewise real, likewise designated.

The Hizamaru / Kumokiri — "Spider Cutter" — is the blade from the tsuchigumo fight, and it comes with a documented lineage of ownership and renaming.

And there are sword-guards engraved with the battles, held in the Tokyo National Museum and in the Museum of Fine Arts in Boston.

Think about what that means for a second. Every folk tradition on earth has monster-slayers. Japan is the one that kept the equipment, catalogued it, authenticated it, gave it state protection, and put it under glass with a label.

The monsters are legend. The gear is inventory.

The civil service reading

Put Raikō's file next to the others and a shape appears that nobody in the Heian period would have described this way, but which is plainly there.

Abe no Seimei and the Bureau of Yin and Yang detect — they read the omens, identify the cause, name the entity, set the date.

Raikō and the Four execute — they go out, and the thing stops.

And the court files the swords — designates them, records them, and passes them down through named owners for a thousand years.

Detection, enforcement, and an evidence room.

Heian Kyoto ran what amounts to a complete supernatural civil service, and the case files of its enforcement arm became the action wing of Japanese folklore.