Futakuchi-onna

There is a second mouth on the back of her head.

It's hidden under the hair, at the base of the skull. It has lips and teeth and a tongue, and it talks — muttering, complaining, demanding to be fed. And when it wants food, her hair moves on its own, dividing into tendrils that reach out, take what's within range, and carry it back to feed the mouth.

The rest of her is an ordinary woman. That's the point.

The story it comes from

The tale is called Kuwazu-nyōbō — "the wife who doesn't eat" — and the setup is a joke at a man's expense.

There is a miser. He is looking for a wife and his requirements are simple: she must not cost him anything. So when he meets a beautiful woman who tells him she never eats at all, he cannot believe his luck. He marries her immediately.

And she doesn't eat. Never at a meal, never in front of him, not once.

But his rice stores keep going down.

So he hides one day and watches her, and what he sees is the hair at the back of her head parting, and underneath it a gaping mouth, and the hair working in handfuls to feed it.

The punishment is beautifully exact. A man who wanted a wife who ate nothing got one with twice the appetite and no way to see it happening. His stinginess didn't just fail to save him money — it selected precisely for the thing that would ruin him.

The darker origins

That's the comic version. The other explanations are not comic at all.

One says the mouth is an axe wound. A blow to the back of the head that never healed properly, and instead of closing, became a mouth.

The other is the one that reframes the whole creature. It says the second mouth is the lodged spirit of a stepchild who was starved to death — a woman who withheld food from a child in her care, now carrying that child's hunger in her own skull, forever, and having to feed it.

Read that version and the futakuchi-onna stops being a story about a greedy wife and becomes a story about what the household did to the child nobody was obliged to feed.

The pattern worth naming

Set her beside her neighbours in this tradition and something uncomfortable comes into focus.

The rokurokubi is a woman whose neck stretches enormously at night, usually without her knowledge — she is asleep, she has no idea, and she is often horrified when told. The kuchisake-onna, two centuries later, is a woman disfigured by a man with a blade who now does the same to children.

And the futakuchi-onna is a woman carrying a mouth she did not ask for.

The consistent shape is this: a female body made monstrous, with a moral pinned to it, and very often the sin being punished is a man's. The miser's greed surfaces on his wife's skull. The household's cruelty to a stepchild surfaces on the stepmother's body. The woman is where the story keeps its evidence.

That's the standard scholarly reading and it's visible in the primary material without any squinting. It doesn't make these stories less good. It does mean they're about something other than what they claim to be about.