Hwangjega Nareul Sihanburago Saenggakaeseo Gollanhada

As his strongest knight, Lindelle helped the emperor ascend the throne. But at his coronation, she coughs up blood–a side effect of her contract with the dragon Laroque, who promised to grant Lindelle any wish if she can find the dragon’s real body. Meanwhile, Laroque’s magic is destroying Lindelle’s body, and the only way to heal is to fulfill the contract. But the emperor’s word is law–and he says Lindelle can’t leave until he finds a cure!
(Source: Tapas)
Note: Includes one extra chapter.