Like the other animals-typed Yōkai, they can shapeshift at will between different shapes, mostly that of a Human, a Weasel, or a mix of the two. They do not seem to prefer to shape into males or females Humans. They are mostly seen in their animal shape, though.
Sneaky and aggressive, they are naturally stealthy and mischevious. They enjoy hurting and scaring their victims instead of killing them, despite being quite powerful. They could be compared to the "ninja" of the Yōkai World. Quick and ressourceful.
Sometimes a person walking in the mountains will be beset by a ferocious wind, and only later will they discover the deep but painless gashes made in their skin as if by some very sharp instrument.
This is said to be the work of the kamai-tachi, a weasel-like creature that rides in a whirlwind, and is equipped with very sharp sickle-like claws with which to attack humans.
In Gifu prefecture, the kamaitachi is said to work in teams of three, the first rushing upon and stunning the victim, the second cutting with its claws, and the third applying medicine that eliminates pain and stifles the bleeding. Sometimes the three are described as brothers, sometimes as triplets.