I Turned Against You After Becoming My Sworn Enemy.

[The detailed work of the princess × the feudal war king] Lin Wanyi, a sharp blade inspired by a mother imprisoned in a deep palace. Following the secret orders of the emperor and the queen mother, she lurked beside Gu Xuanjin, the highly accomplished king of Zhenbei, in the name of a concubine, just to find a fatal blow. The land was bitterly cold, but the people's hearts were warm. She saw with her own eyes that under Gu Xuanjin's rule, the Qingming people returned to their hearts, far better than the sinister emperor on the Dragon Throne. A heart that had been trained to be ice melted quietly under his careless protection. A secret love arose, and Gu Xuanjin's love made her feel like she was falling into the abyss. She struggled between loyalty, filial piety and conscience, until her identity was exposed, and the queen mother of the fiefdom was furious, with a sharp sword hanging from her neck, life and death on the line. "It's easy to kill me," Lin Wanyi looked directly into Gu Xuanjin's bottomless eyes and vowed resolutely, "But let me live. I am willing to be the prince's sharpest chess piece to help you... Conquer the world! When you wear the yellow robe, it will be the time when I am stained with blood on the dragon chair!" He accepted this fatal chess piece, but he did not know that on the chessboard of power and intrigue, the most difficult killing move is to bury the one he loves with his own hands. When the road to the supreme position is paved with her blood, can Gu Xuanjin still wield the last sword?