Futakuchi-onna: Though there are several stories linking the appearance of a futakuni-onna’s second mouth to different causes, it is most often linked to how little a woman eats. The soon-to-be futakuchi-onna is usually a wife of a miser and rarely eats. To counteract this, a second mouth mysteriously appears on the back of the woman’s head. The second mouth often mumbles spiteful and threatening things to the woman and demands food. If it is not fed, it can screech obscenely and cause the woman tremendous pain. Eventually the woman’s hair begins to move like a pair of serpents, allowing the mouth to help itself to the woman’s meals.

and

Kawa-Uso :A folkloric otter with supernatural powers