Namdongsaengi Kkotgireul Gangyohanda

Shortly after becoming empress in her second life, Raviel Sutton realizes she desperately needs a slave, er... husband. Her brother Edwin Sutton, aka "the lunatic," takes matters into his own hands and comes up with a scheme that basically assures Raviel ends up with the dashing Duke Haven Derhardt. As Raviel battles attempts on her life and political intrigue, she must hide the knowledge of her past life from the two men dearest to her⁠—although they seem to have plenty of secrets of their own.

(Source: Tapas)