Kouyoukoku Koukyuu-tan: Kokui no Shugo

The reign of the 13th emperor of the glittering country. A lonely girl, Shouko (Xiao Hu), fights to protect her only sister. Under the supervision of Sou (Cang), a government official who noticed her ability, she was assigned to a certain job while dressed in black. Then she meets the emperor, Shuug