Kuko is is a type of kitsune found in Japanese folklore and mythology, believed to be the third and final stage of evolution for good-aligned kitsune and have obtained a state of power equal to those of the gods, however despite being supremely powerful they no longer actively engage in contact with the physical world and instead tend to act as a venerated elder within the grander cosmology (this is also why Tenko rank higher than them in good kitsune society, despite Kuko being stronger in terms of magical ability).
Despite this a Kuko may at times possess a foolish human to try and teach them how to improve their lives, unlike other kitsune possessions when a Kuko takes control of a human they do not cause any madness or ill effect.
As with the Tenko and Kiko they are no longer physical beings and are considered pure spirits, thus can take any form they desire but tend to resemble humans with kitsune alterations (such as ears), they no longer have the distinctive kitsune tails.