The Substitute Queen

Forced to be a substitute bride for my eloped sister, my groom is the Ghost-Faced Prince, a ruthless killer. Unexpectedly, this Warlord Prince dotes on me. But when my arrogant sister returns, demanding her place back, I meekly acquiesce. The next time we meet, she is a prisoner, and I have become the Demon Empress, the true power behind the throne.