Ushi-oni

An ox's horned head, on —

Depending on where you're standing: a spider's body, an oni's frame, or, in one Izumo tradition, a shining white butterfly.

The ushi-oni is western Japan's shape-unstable demon, and the instability is the entry.

Three relationships with three communities

On the San'in coast, it is a man-killer.

In Kagawa, it is a monster that was slain, and whose horns are kept.

In Uwajima, it is a beloved festival giant, paraded through the streets by volunteers.

One name. Three completely different arrangements with the people who keep it.

The standard form, and the exceptions

The catalogues fixed a shape: ox head, sharp upward-curving horns, wicked fangs, a slender tongue, and a spider-like body.

That's the version in the 1737 scroll and in Sekien.

But the regional forms don't even share anatomy.

Some invert it — an oni's head on an ox's body.

And Izumo has the white butterfly, which is not a modification of a monster. It's a different creature entirely, wearing the same name.

Variance as the data, not as noise.

The hunting pair

On the San'in coast the ushi-oni doesn't work alone, and this is the only cooperative predation in the whole collection.

The nure-onna — the wet woman, snake-bodied, hair always dripping — meets you at the shore and asks you to hold her baby.

The bundle becomes impossibly heavy. You can't run with it and you can't put it down.

And then the ox-demon comes out of the surf.

She immobilizes. He kills.

Nothing else in Japanese folklore has a partner. And there's a small confirmation in the printing: Sekien's catalogue puts the ushi-oni and the nure-onna adjacent in volume three — the plates preserve the partnership.

The temple keeps horns

Negoro-ji, in Kagawa, holds horns said to be from an ushi-oni slain by the archer Yamada Kurando Takakiyo, by a tradition dating to around the 1600s.

Which puts it on the same shelf as the demon claws in shrine treasuries and the mermaid mummies in temple collections: trophy relics, kept, catalogued, and shown.

(The details of the legend and the horns' own history I'd want to verify before stating flatly.)

And in Uwajima it leads the parade

At the Warei Festival in Uwajima, Ehime, the ushi-oni floats come out.

Enormous multi-person constructions — long cloth bodies stretched over frames, carried by teams, with carved painted heads on poles swinging at the front, moving through the streets.

As protective figures.

The man-eater, domesticated into a civic mascot.

Which is the same arc this tradition runs constantly, compressed into one prefecture's calendar: the thing that came out of the surf to kill you now leads the summer festival, and children are lifted up to see it, and the town pays for its upkeep.

The demon on the roof tile. The demon in the parade. The demon with a maintenance budget.

Same principle every time: once it's yours, the frightening face is on your side.