In Japanese Mythology and Folklore, who is a type of Japanese 'Yokai' that is characterized by two mouths?

A Japanese 'Yokai' are a class of supernatural entities and spirits in Japanese Folklore. The word 'Yokai' is composed of the Kanji for "attractive; calamity" and "apparition; mystery; suspicious". 'Yokai' are not literally demons in the Western sense of the word, but are instead spirits and entities, whose behavior can range from malevolent or mischievous to friendly, fortuitous, or helpful to humans.

In Japanese Mythology and Folklore, the 'futakachi-onna' belongs to the same class of stories as the 'Rokurokubi', 'Kuchisake-Onna', and the 'Yama-Uba', women affected with a curse or supernatural disease that transforms them into 'Yokai'. The supernatural of the women in these stories is usually concealed until the last minute, when the true self is revealed.

The origin of a 'Futakuchi-Onna's' second mouth is often linked to how a little woman eats. In many stories, the soon-to-be 'Futakuchi-Onna' is a wife that rarely eats stuff. 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's 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. While no food passes through her normal lips, the mouth at the back of her head consumes twice what the other one would.