From Ardrana

Hengeyokai are a race of intelligent shapechangers. Several subraces exist, each representing a different type of animal. A Hengeyokai can shapeshift between three different forms: animal, biped, and human. Each Hengeyokai can assume only one animal form. The most common are carp, cat, crab, crane, dog, drake, fox, hare, monkey, raccoon dog, rat, and sparrow.

When in animal form, the Hengeyokai is indistinguishable from normal animals of its kind. The change in form is genuine.

When in bipedal form, the Hengeyokai looks like a humanoid animal. He stands on his hind appendages to the height of a normal man. The front appendages (wings, paws, or fins) change into hands, capable of gripping and using normal weapons. The rest of the body retains the animal's general appearance, including fur, feathers, wings, a tail, and other characteristic features.

When in human form, the Hengeyokai looks like a normal Human. Like the animal form, the human form is genuine and cannot be detected by spells that reveal illusions. However, the human form always retains one or more distinctive features of the animal form. For instance, a sparrow Hengeyokai may have a pointed nose, and a rat Hengeyokai may have beady eyes and long whiskers.

Hengeyokai have their own language, which is the same regardless of their animal type. They can speak this language in all three of their forms. Additionally, Hengeyokai can converse with normal animals and speak the trade language, as well as the languages of humans in the area. Hengeyokai only can speak human languages when in their human or bipedal forms.

On Ardrana, the most common hengeyokai are of the cat subrace, and they are typically found only in Jiberia. However, they have been known to travel to other areas, and of course there may be others that keep themselves well-hidden. They live mainly in the shadow of the Onyl Mountains, and occasionally have been known to interact with the Tiger clan, whose lands lie closest to their homeland. There is also a population of Hengeyokai in the Vykhar Mountains in the eastern Cardillic Desert.

Note: Hengeyokai originally appeared in this form in the Kara-Tur Monstrous Compendium Appendix for the AD&D game from TSR. Their use here is for the purposes of providing context for the campaign only.