Seijo to Sumeragi Ou no Seiyaku Kekkon Hazukashii no de Seijo no Jiman Banashi wa Shinaide kudasai ne!

The Ezelta empire has long been on the verge of losing a fierce war, but it has now come to pass. After losing the war, Saint Julietta makes every effort to protect the livelihood of new emperor Luchino and the citizens of the empire, all while resolving herself that Emperor Luchino could sentence her to death at a moment's notice. But she soon discovers he's very kind and, after he reminds her of an oath she made 400 years ago, she ends up marrying him?! "You can still win this war," she tells him... So with her hidden power, she begins to bring about a miracle!