The Lost Royal Obey Me

MC continues to have the same nightmare over and over again. they are running through a forest being chased by someone when they trip allowing the person to catch up with them, but when they look at the person a sense of deja vu comes to them. after this happens a couple of times a box is delivered to them with a book and key inside. the book includes a Fairy Tail about a stolen royal baby but what does the key unlock you're going to have to reed to find out. ;)