She is the daughter of a benevolent nine-tailed kitsune (nine tailed fox spirit) and an ascetic monk who fell in love with each other and went against the rules to ensure her safe birth. Although she is half human, she was able to gain her nine tails by undergoing a test of death and rebirth given by the council of the thousand year old kitsune (giving her white streaks in her hair) and bestowing her great wisdom and power.
She is one of the Keepers of the four corners, which are a consortium of very powerful magewarriors entrusted to protect the realms of the Elementalist, safeguarding peace all throughout the parallel worlds.
SC, the nine tailed fox is a common character in Japanese stories. Yea, it shows up in Naruto, as well as Yu Yu Hakusho, and other anime series that escape me at the moment.