A traditional Japanese monster, a nopperabou appears human in all respects, except for the fact that it has no face. The front of a nopperabou's head is smooth, blank skin.
Strangely, nopperabou do not seemed to be handicapped by their lack of orifices. In stories told of them they seem perfectly capable of sight and speech, and even tears despite their lack of eyes or a mouth. Sometimes, a nopperabou can appear to have a face, but it seems this is an illusion that they effect, facelessness being their natural state.
Unlike other Japanese monsters such as oni or gakidou, nopperabou seem to lack a background myth to support why they exist. They are simply creatures people sometimes encounter. It seems that nopperabou enjoy frightening people, but lack any larger agenda. It is possible that in their facelessness they represent the atavistic fear of the other.
Nopperabou were first popularized with the publishing of the story "Mujina" in Lafcadio Hearn's collection, "Kwaidan"