The Evil King and Mad Concubine Who Is Reborn as a Waste Material

She was originally the most powerful undercover agent in the 21st century, but accidentally traveled to a strange continent, and tragically became a drug tester for a pair of vicious sisters; he was the most feared evil king on the continent, but he favored her, whom everyone disliked; everyone thought she was not worthy of him, but he was still willing to pamper her alone, pick stars for her, travel nine continents for her, conquer the world for her...