We Don't Know Each Other Anymore

"The reason I am leaving this letter—though you may already know—is to keep a promise." Elisha, the Archmage of the Cardion Empire and fiancée of Emperor Erich. "Your Highness, no, you know what His Majesty the Emperor always used to say. 'I will never marry you, not even if I die!'" One day, she suddenly vanished, leaving only a single letter behind for her fiancé. However, contrary to Elisha's expectation that he would not look for her, Erich immediately began searching for her... "Whether she is within the Empire or has left the country. I just have to find her and bring her back." If he finds her and brings her before his eyes, then... "We must make a new promise."