Eila to Totsukuni no Ou

As part of an arranged political marriage, Eila is forced to travel to the country of Lottefeltz, and marry the beautiful Prince Errold. As soon as she meets him, he steals her heart, but there is something unsettling about the castle. There is a rumor about girls who enter the castle grounds... it is said that once they enter its walls, none of them are ever seen again. Could these terrifying rumors be true...?