The black mirror BM

Three hundred years ago, the Demon Lord Zhao Li sacrificed several thousand offended souls to create a wish-fulfilling mirror that later led to his death. After his death, the new Lord Shi Yu got rid of a dangerous artifact that could be used against him.
When the scarlet immortal Aoi appears in the human world to find the fragments of the black mirror, Shi Yu decides to kill Aoi, but an unknown caster interferes with his plans.