Origin: Japan
Futakuchi-onna (or The Two Mouthed Woman) is an urban legend about a woman who is cursed with having two mouths, one normal mouth at the front and another hidden, monstrous mouth in the back of her head.
Futakuchi-onna is a monstrous woman with a tiny mouth. However, on the back of her head, hidden beneath her hair, she has a huge second mouth. The women's skull splits apart, revealing lips, teeth, and a tongue. Although she appears to never eat, the mouth in the back of her head is ravenous and consumes huge quantities of food.
They say that the big mouth has a mind of its own and speaks to the woman, mumbling spiteful and threatening things to her. The mouth will harass the woman and threaten her, demanding food. It will screech obscenely and cause the woman tremendous pain until it is fed. The monstrous mouth can also control the woman's hair, making it snake out like tentacles, grabbing food and shoveling it down its throat.
There is some disagreement in Japan as to Futakuchi-onna's origins and how she got her second mouth.
One story from Japanese folklore tells of an old miser who lived by himself in a small village. He never got married because he hated spending money. He thought that if he took a wife, he would have to pay for her food and he could not bear the idea of parting with his wealth.
It so happened that he came across a young woman who did not eat a thing and immediately asked her to marry him. Because she seemed to never eat and was a hard worker, the old miser was thrilled that he had found the woman of his dreams and the couple were very happy together. However, he began to wonder why his stores of rice were steadily decreasing.
One day, the old man pretended to leave for work but instead stayed behind to spy on his new wife. To his horror, he saw his wife's hair part on the back of her head, her skull split wide open, revealing a gaping, deformed mouth. Her hair reached out like tentacles, grasping handfuls of rice and shoveling it into the monstrous mouth.
When the woman noticed her husband had discovered her secret, she attacked him and tried to strangle him. He managed to get away and hid in the mountains. Weeks later, when he worked up the courage to return, he found that the woman had gone and all his stores of rice had been eaten. The old man never married again.
In another story, a man's wife died, leaving him with a daughter to care for. The man remarried, but his new wife was a very mean and vindictive person. Together, they had a second child, another daughter. However, they were poor and there was barely enough food to go around. The new wife decided to keep her own daughter fed, while she starved the other girl. The man's daughter eventually died of starvation.
Not long after, the man was out in the garden, chopping wood for the fire. He accidentally swung his ax incorrectly and embedded it in the back of his new wife's head. There was a lot of blood and he expected the woman would die. She survived, but the open wound would never heal. Instead, it formed into a huge, drooling mouth, complete with teeth and a tongue.
The woman was in tremendous pain and the only way to make it stop was to feed the deformed mouth. It demanded more and more food to keep it satisfied. Eventually, the mouth began making sounds and started talking. One day, while the woman was asleep, the hideous mouth spoke to her husband and confessed, "I am cursed because I killed your daughter by starving her to death!"