Title: Abi’s Gods and Monsters #2
A Japanese demon called a Futakuchi-onna.
Wiki syas: A futakuchi-onna (二口女?, lit. “two-mouthed woman”) is a type of yōkai or Japanese monster. They are characterized by their two mouths – a normal one located on her face and second one on the back of the head beneath the hair. There, the woman’s skull splits apart, forming lips, teeth and a tongue, creating an entirely functional second mouth.
In Japanese mythology and folklore, the futakuchi-onna belongs to the same class of stories as the rokurokubi, kuchisake-onna and the yama-uba, women afflicted with a curse or supernatural disease that transforms them into yōkai. The supernatural nature of the women in these stories is usually concealed until the last minute, when the true self is revealed.