Ikaruga Tsubasa

The only surviving member of the Ikaruga Clan, which was a family of famous onmyouji that were wiped out when they ran into one of the few god-class Magatsu out there. She is more or less at peace with what happened, but she is driven by a sense of duty to rebuild the clan. She gets involved with Hayato and Shion by accident and ends up being their minder at the request of the nation. She is actually the older brother of a pair of twins that got transferred into his little sister's body during the disaster. She is still coming to terms with her body and guilt for taking over her sister's body.

Spoiler

In reality, she is a chimeric soul made up of the shattered remnants of the original Tsubasa's and Satsuki's souls, grafted together by accident by the power of the Magatsu that killed them both.