Toriyama Sekien's picture books are full of monsters he plainly invented on the spot, and Jakotsu-baba may be the clearest case of him showing his work. In the entry for her in Konjaku Hyakki Shūi (1781), he doesn't just draw her — he explains, in a short prose note beside the image, exactly where he thinks her strange name came from. It's less a ghost story than a scholar's footnote that got loose.
What does she look like?
Sekien's Jakotsu-baba is an old woman, hunched and grim-faced, gripping a snake in each hand — a blue one in her right, a red one in her left. There's no shell, no dish, no obvious monstrous feature; she reads as human until you notice what she's holding, and how calmly she holds it. Later retellings describe her body as wrapped in serpents rather than simply carrying them, but the core image, two snakes and an old woman who has clearly made her peace with both, comes straight from the original print.
A widow at the snake mound
According to Sekien's note, Jakotsu-baba once lived in a land called Bukan (also read Fukan; Wuxian in Chinese), a country described in the ancient Chinese geography text Shan Hai Jing as populated entirely by shamans skilled in reading omens from snakes. Her husband was a man named Jagoemon, who made his home at a place called "the snake mound." After his death, Sekien writes, the mound became his grave — and Jakotsu-baba stayed there to guard it, driving off anyone who came too close with the two serpents she kept at her side.
Over time, Sekien theorizes, the name "Jagobā" — literally "Jago's wife" — wore down through repeated telling into "Jakotsu babā," the snake-bone hag. It's a folk etymology, offered as an explanation rather than a fact he claims to have verified, and that honesty is part of what makes the entry unusual among his hundreds of yokai.
A word before it was a monster
The phrase jakotsu babā did not start with Sekien. It shows up decades earlier, in the pulp fiction and kabuki plays of the 1760s and 1770s, as ordinary slang for a frightening or ill-tempered old woman — closer to an insult than a name. Some scholars think Sekien picked up that already-circulating phrase, decided it deserved a face, and built the Bukan legend around it to give a piece of everyday abuse a proper origin story. If that's right, Jakotsu-baba isn't a monster that got a name; she's a name that got a monster, worked backward from a Chinese classic Sekien had clearly been reading closely.
Where it comes from
No version of this story predates Sekien's own book, in either Japanese or Chinese sources, which is part of why the "he made it up" theory has staying power. What isn't in doubt is his source material: the Shan Hai Jing's account of Bukan and its snake-reading shamans was real and available to an Edo-period reader, and Sekien's habit throughout his four picture-book series was to graft new characters onto exactly this kind of half-remembered continental scholarship. Jakotsu-baba sits at that graft point — a woman as real, within the fiction, as the country he says she came from.
After Sekien
Later writers didn't leave her at the snake mound. Some Shōwa-era folklore collections relocate her grave-keeping story to Japan itself, quietly dropping the Bukan framing and letting her stand as a homegrown hag. The folklorist Minakata Kumagusu, writing on snake lore, also noted a related figure used as a household charm against venomous snakebite — a small sign that the "old woman who controls snakes" idea had some life outside Sekien's page, even if her specific name and backstory stayed his.
She never became a household yokai the way the kappa or the fox spirit did. There's no cucumber ritual attached to her, no proverb, no mascot. What survives is the picture — an old woman, two snakes, a grave she won't leave — and Sekien's own uncertain footnote trying to explain how she got there.