Futakuchi-onna

In Japanese mythology, Futakuchi onna (Japanese: 二口女 or ふたくちおんな, meaning "two-mouthed woman") are most often thought to be shape-changed yama-uba posing as young women who eat more food than a normal young woman.

Families which notice their food stocks are shrinking at an alarming rate while the women in their houses rarely eat a bite may be the victims of a futakuchi onna infestation.

In the western regions they are frequently shape-changed magical spiders. In the other tales they are the result of curses brought about by wicked deeds, similar to Rokurokubi (long-necked women). In each story, regardless of its true nature, this yokai is used as a punishment upon a greedy man or woman for wickedness and extreme parsimony.

Myths & Legends
In a small rural village in Fukushima there lived a stingy miser who, because he could not bear the thought of paying for food to support a family, lived entirely by himself. One day he met a woman who did not eat anything at all, and he immediately took her for his wife. Because she never ate a thing, and was still a hard worker, the miser was thrilled with her. However, his stores of rice were steadily decreasing, and he could not figure why, for he never saw his wife eat.

One day the miser pretended to leave for work, but instead stayed behind to spy on his new wife. She untied her hair, revealing a second mouth on the back of her head, complete with ghastly lips and teeth. Her hair reached out with tentacle-like stalks and began to scoop rice balls into the second mouth, crying out in pleasure in a vulgar, raspy voice.

The miser was horrified and resolved to divorce his wife. However, she learned of his plan before he could act on it, and she trapped him in a bathtub and carried it off into the mountains. The miser managed to escape, and hid in a heavily-scented lily marsh, where the futakuchi-onna could not find him.

Another story tells of a wicked stepmother who always gave plenty of food to her own daughter, but never enough to her stepdaughter. Gradually the stepdaughter grew sicker and sicker, until she starved to death. Forty-nine days later, the wicked stepmother was afflicted with a terrible headache. The back of her head split open, and lips, teeth, and a tongue formed. The new mouth ached with debilitating pain until it was fed, and it shrieked in the voice of the dead stepdaughter. From then on the stepmother always had to feed both of her mouths, and always felt the hunger pangs of the stepdaughter she murdered.

Appearance
Futakuchi onna appear just as a regular women until their terrible secret is revealed: in the back of their skulls, buried beneath of long, thick hair, is a second mouth, with large, fat lips, and full of teeth. This second mouth is ravenous, and uses long strands of hair like tentacles to gorge itself on any food it can find.