The Noppera-bō

The Noppera-bō (のっぺら坊, Noppera-bō^?), or faceless ghost, is a Japanese legendary creature. They are sometimes mistakenly referred to as a mujina, an old Japanese word for a badger or raccoon dog. Although the mujina can assume the form of the other, noppera-bō are usually humans. Such creatures were thought to sometimes transform themselves into noppera-bō in order to frighten humans. Lafcadio Hearn used the animals' name as the title of his story about faceless monsters, probably resulting in the misused terminology.
Noppera-bō are known primarily for frightening humans, but are usually otherwise harmless. They appear at first as ordinary human beings, sometimes impersonating someone familiar to the victim, before causing their features to disappear, leaving a blank, smooth sheet of skin where their face should be.
The Mujina of the Akasaka Road
The most famous story recollection of the Noppera-bō comes from Lafcadio Hearn's book Kwaidan: Stories and Studies of Strange Things. The story of a man who travelled along the Akasaka road to Edo, he came across a young woman in a remote location near Kunizaka hill, crying and forlorn. After attempting to console the young woman and offer assistance, she turned to face him, startling him with the blank countenance of a faceless ghost. Frightened, the man proceeded down the road for some time, until he came across a soba vendor. Stopping to relax, the man told the vendor of his tale, only to recoil in horror as the soba vendor stroked his face, becoming a noppera-bō himself.
There are other tales about noppera-bō, from a young woman rescued from bandits by a samurai on horseback whose face disappears; to stories of nobles heading out for a tryst with another, only to discover the courtesan is being impersonated by a noppera-bō.

citation: http://en.wikipedia.org/wiki/Noppera-b%C5%8D