Kon

Harutora's shikigami. A diminutive silver-fox spirit who wears miko-like clothing and wields a wakizashi and has served the Tsuchimikado clan since a long time. She has been by Harutora's side since the moment he became Natsume's shikigami, but due to his low spiritual power and awareness, he was unable to hear or see her. A rare Gohou-type shikigami, she possesses independent thought and actions and is fiercely loyal to her master, and even gets jealous when Harutora associates with other girls.

[Spoiler] Shortly before Harutora's awakening as Yakou, Kon reveals her true identity as Hishamaru, one of Yakou's two lengendary familiars who had 'disappeared' after his death. Kon forcefully destroyed her 5 seals restoring her true power and her appearance as Hishamaru. Her first seal hides both itself and the other seals, the second seals her personality, the third seals her appearance, the fourth seals her power, and the final seals her memory. [/Spoiler]

(Source: Wikipedia)