Irazu no Hime wa Jinrou no Kuni de Aisare Ouhi to naru!

Ermengarde, Princess of the Bral Empire, disappears before her marriage to King Ivan of Shenka. In order to ensure the success of the 'political marriage' between the human kingdom of Brar and the werewolf kingdom of Shenka, Ermengarde's twin sister, Ernesta, is selected instead. Ernesta has been declared dead as an 'abomination' and lives as an ordinary person. Ernesta marries into Shenka on the condition that her ailing mother-in-law is treated by the country's best team of doctors. A 'sham marriage' begins, with the fate of the country at stake!