While a good amount of hengeyokai can pass for ordinary animals, become slightly malformed by their transformation, usually gaining an extra tail. Even when shapeshifted, the animal's true nature may be exposed by a body part that won't transform (again, usually the tail), vaguely bestial features, or markings remeniscent of their true form. The hengeyokai may also be exposed by their appetites -- many a cat hengeyokai is exposed by being caught eating dead birds while in human form.
The hengeyokai are primarily tricksters, using their abilities to steal or cause minor inconvenience to surrounding human populations. Especially malevolent hengeyokai will take on the form of a person in a household, murder them, and take their place. Animals prone to transforming are foxes (kitsune), racoon dogs (tanuki), cats (bakeneko), badgers (mujina) and dogs (inugami).