Futakuchi Onna

Futakuchi Onna (literal translation "Two mouthed woman") is a curse that appears in Japanese folklore, affecting solely married women. The manifestation of said curse appears as a large mouth with sharp teeth on the back of the woman's head. Upon the manifestation of the mouth, the woman hosting the mouth, is, herself, considered a yōkai (supernatural entity).

The cause of this affliction is often credited to how much the woman in question eats. Many stories involving Futakuchi Onna center around a woman, married to a greedy miser, who rarely eats. Because of this, the mouth manifests, with the woman's hair moving like tendrils to help consume any food in sight. The mouth appears secretive, often hiding itself until the last minute in most tales.

Another lesser known manifestation of Futakuchi Onna is caused by a married woman who neglect her step children to the point of death. The step-child in question then latches onto the step-mother and manifests their hatred as a mouth. While not dangerous or violent, the mouth is often described as vulgar and rude, constantly demanding more food, and insult those who refuse its demands.