The Eighth Bride in the Abyss

To save his sister, Laine, a man, disguises himself as a sacrificial offering. The Dragon King Azael saves him and declares him his fated mate and eighth bride, even though the previous seven brides all died horribly. Laine at first refuses to marry another man, yet he falls in love with Azael without realizing it—but he does not know that the price of breaking the Dragon King's curse will be his own life.