Gutaika

She is the personal summon of Renya, originally from the land of Shinkyō, though currently affiliated with Eigakure, and one of a few female sages.

Outline
She is an exceptionally powerful fox that is one of the few females to become a sage, giving her the ability to pass one her teachings to her summoner. She is said to be a prodigy in the use of genjutsu even by most foxes's standards. Like Soji (whom she is good friends with), Gutaki-Ka cares for her summoner as if she was Gutaki-Ka's own child.