Reina, the second princess of the kingdom of Fromesia, has been oppressed as the daughter of a concubine since childhood. After her country's defeat in the war, she is forced to marry in the land of the beastmen, in place of her sister-in-law, as a condition of peace. She marries the Dragon King Cain, who is rumored to be the "most fearsome" man in the world, but there is a beautiful man with golden eyes! Blessed by Cain's consideration and the good-hearted beast-men, Reina completes the wedding ceremony without incident. However, on the wedding night, Cain coldly rejects her, telling her that "this marriage is only superficial."