Mujina.

Mujina (貉, むじな) originally refers to a badger-like animal, but in folklore the word expands into a shape-shifting yōkai with unstable boundaries. In some regions it clearly means badger, in others raccoon dog, and in still others a broader class of magical burrowing mammals. That fluidity is part of the creature's character rather than a problem to solve away. Mujina already lives in the zone where taxonomy begins to slip.

When transformed, a mujina can appear in many human and nonhuman guises. It may become a small monk, a woman on the road, a local official, a strangely luminous traveler, or the faceless form later associated with noppera-bō. The important constant is not one shape but the trick itself, the sense that what looked ordinary a moment ago was never fully what it seemed.

Mujina are primarily tricksters. They sing at night, mislead travelers, imitate human speech, and test how far a disguise can carry them before someone notices the flaw. Many stories are mischievous rather than lethal, which sets them apart from harsher mountain or revenge yōkai. Even so, a mujina can become dangerous if provoked, cornered, or if its den and family are threatened.

Their most famous interaction in later reception comes through faceless transformation. A traveler meets what appears to be a person, then sees the face vanish into smooth skin. This has often been mislabeled simply as a 'mujina' because of Lafcadio Hearn's famous retelling, but the underlying folklore is more complicated. Mujina can use that form, yet not every faceless apparition is a mujina, and the confusion itself became part of the tradition.