Jakotsubaba

An old woman with a great serpent coiled around her body. Sekien drew her in 1781.

And in his caption he did something he almost never does: he admitted he didn't know.

He offers two possible origins, and then writes 未詳 — "unclear."

That's the entire attested content of this creature. A picture, two guesses, and a shrug from the man who drew it.

The two guesses

One: she might come from the Shanhai Jing, the ancient Chinese book of strange lands, which describes a nation whose people carry blue and red serpents in each hand.

Two: she might be the wife of a man called Jagoemon, associated with snake mounds.

That second one is worth pausing on, because Jagoemon exists nowhere else. No other source mentions him. He is a husband invented to explain a wife, in a caption that then says the whole matter is unclear.

And then everyone filled it in anyway

Here is why this small entry matters more than it looks. The accretion is unusually traceable, and it happened over the author's explicit objection.

1972. A writer named Satō Yūmon relocates her to "the remote mountains of Tōhoku" — coordinates that were never in Sekien — and gives her serpents elemental jobs: one freezes, one burns.

Later yokai books. Jagoemon is recast as an imprisoned snake demon, sealed in a burial mound — and his wife is now standing guard over the prison, faithfully, forever.

That's a complete gothic novella. A location, a supernatural power set, a doomed husband, a sealed tomb, and a widow's vigil.

All of it grown out of a shrugged footnote.

This is the sharpest specimen in the collection of a specific failure mode: accretion with the original author dissenting in advance. Sekien wrote "unclear" on the package. Two centuries of editors shipped it anyway, and every addition made the creature more satisfying and less true.

What she probably was

There's a solvent, from the scholar Kondō Mizuki, and it's deflating in the way these usually are.

The name likely began as derisive eighteenth-century slang for old women.

Not a creature. An insult. A word people used about their neighbours, which Sekien encountered, took as the name of something, and drew.

That mechanism turns up repeatedly in his catalogs — a piece of ordinary spoken language, mistaken for or deliberately treated as a proper noun, and given a body. The insult comes first; the monster comes second.

Which leaves the jakotsubaba in a strange position: a picture of an old woman, built from a rude word about old women, footnoted as unverified by its own author, and then given a home, a husband, a prison, and a pair of elemental snakes by people who never read the footnote.