Haiiro No Onmyouji

Sabatora, a boy whose parents were killed by Kuremyō, works as an Onmyoji for the Public Security Bureau to get revenge. His only comfort is Kyue, a Kuremyou who lives with him. Kyue, who has lived with Sabatora since he was a small child, is a kind and gentle soul who is like an irreplaceable member of Sabatora's family. One day, however, Kyue is attacked by Seto, a colleague from the Public Security Bureau who hates Kuremyei. In a pinch, Sabatora and Kyue undergo an unexpected transformation.
(natalie.mu)