The Castle: Keeper of the Sacred Eye

Yuyeon Jo possesses a unique gift: the power to see invisible demons. Her gift is exactly what Geon Lee, the Crown Prince of Korea, has been searching for. Descended from a long line of demon exorcists, Geon bears a royal duty to find a bride who can assist him in protecting his country from monsters. What Yuyeon doesn't know-or rather, doesn't remember-is that she and Geon share a history that dates back to the day a tragic accident killed her father thirteen years ago. What precisely happened on that fateful day, and will Geon forgive her for lying about her gift to save her mother, who has been unconscious since the accident? Yuyeon had never been happy with her ability to see demons, but perhaps now, her Sacred Eye could prove invaluable-not only for the safety of Korea, but for her own chance at happiness and true love.

(Source: Webtoon Entertainment)