… the Oni race

Oni are a race of demihuman females. Generally petite, curvaceously sexy, primitive, unintelligent, sensual and uninhibited humanoids with horns on their temples and oddly hued skin… they are highly prized by the wealthy as sex slaves and pets.

They are often caught and domesticated for this purpose and whilst stronger than a human they are quite docile and obedient.

There is one attribute about them that is not widely known. If a human is injected with Oni blood, whether male or female, they will rapidly transform into an Oni, shrinking down in size and finding themselves as highly sexed and submissive demihumans. There is no cure for this transformation and such Oni are easily enslaved as sex slaves and pets.