Tokyo Ravens

Tokyo Ravens (東京レイヴンズ, Tōkyō Reivunzu) is a Japanese light novel series written by Kōhei Azano and illustrated by Sumihei. It was adapted into a manga series in 2010. It received an anime series on October 9, 2013.

Plot
In some event known as the "Great Disaster," Japan has been thrown into chaos by onmyouji (a kind of magician). Harutora Tsuchimikado was born into an onmyouji family, but he has no power whatsoever. He lived normally as a regular boy, but his estranged sister Natsume Tsuchimikado suddenly appears to him one day. When they were younger, he made a promise long ago to become her shikigami (familiar), and she is back to make him fulfill that promise! A battle between onmyouji is about to begin...