The Secrets Of The Lovely Duchess summary:

Luclia is a girl who was trapped in the demon archduke's dungeon for seven years and saw ghosts. One day the prison wall collapsed and a man came."Wow! are you a prince?""Sorry, I'm just a duke."Davier, Duke of the House of Montenfeltro. Sure enough, with his temperamental and violent personality, he would take Luclia, an unknown girl, as his princess?!"Duke, I wonder why you brought her here..."Luclia, who has just entered the word with the mysterious Duke Davier. Can two people understand each other and still be happy?