Miyabichi no Onmyouji

A time when the boundary between human and demon was vague. Ten sacred items—"Jingi" had been stolen from Mikado's Treasury by some demons. An imperial order to recover the Jingi was given to all the Onmyouji in the capital, including "the heretic"—Fuzuki. He sets out to retrieve the first Jingi, but something unthinkable happened...

(Source: Square Enix, translated)