Toaru Mao to Yusha No Seiryaku Kekkon Nitsuite No Kiroku (Kadokawa Ruby Bunko)

[Machine Translation] One day, the Demon King, who was treated as a pawn of his country and fed up with people repeatedly attacking him, received a letter from a mysterious young man - a letter from the king of an enemy country, which mentioned a political marriage with a brave man. The letter from the king of the enemy country said that the marriage would be a political ploy. The Demon King, who had no right to refuse and reluctantly accepted the marriage, was Reinhardt, the man who had given him the letter. Despite the surrounding speculation, his words of faith in the goodness of the Demon King gradually save the Demon King's heart. However, their loving time together is short-lived, for the Demon King has a sad fate awaiting him that is connected to the memories of the hero's previous life...?

国の駒として扱われ、攻撃を繰り返す人間にも辟易していた魔王は、ある日謎の青年から手紙を受け取る―敵国の国王からの手紙に書かれていたのは、勇者との政略結婚について。拒否権があるわけもなく、渋々婚姻を受け入れた魔王のもとに現れた勇者は、あの手紙を渡してきたラインハルトだった。周囲の思惑をよそに魔王の善良さを信じる彼の言葉は、次第に魔王の心を救っていく。しかし、愛しい時間も束の間、魔王には勇者の前世の記憶に通ずるある悲しい宿命が待っており―?