Yamato Gensouki

Yamato Gensouki summary:

Shion is a young man working for the Onmyou Organization under false pretenses. He is attempting to avenge the destruction of his nation and the deaths of his family members, and targets the Empress in an attempt to destroy her homeland. However, their destinies are in fact entwined, as she not only dislikes destruction, but wishes to unite all of Japan peacefully.