The Dragon King's Surrogate Wife

Quick answer: 10 episodes, English original audio, and episodes 1–10 play right here tonight.

Amelia Vaughn and her twin sister Serena were sent to the Dragon Realm as offerings to its ruler. Jealous of Amelia's rare white fur, Serena forced her to live as a maid, while Serena took the title of the Dragon Lord's wife. Nathan King, Lord of the Dragon Realm, is feared by everyone. Every virgin offered to his bed has died. When Nathan returns from the Abyss gravely wounded, Serena drags Amelia to his chamber and forces her to take her place. In the dark, Nathan can't see her face, only her scent. Amelia whispers that she is his wife. By morning she is still alive, and Nathan's wounds have healed. Amelia slips away believing no one will ever know.

But Nathan can't forget the woman from that night, and the scent that lets him sleep belongs to the maid in the corner, not the wife on his arm. Serena sends Amelia back again and again, promising her a map out of the Dragon Realm. Nathan grows more suspicious each time. The Serena he holds at night is shy and gentle. The Serena he sees by day is cruel. When Serena's stolen witch's blood wears off before the royal wedding, Amelia is forced to walk down the aisle in her sister's dress, ready to say goodbye to the man she has fallen for. But Nathan has been watching all along. As Serena and Elder Drake scheme to keep the crown, Amelia must decide whether to keep hiding behind her sister's face, or claim her place beside the Dragon King and the child she now carries.