Yarinaoshi Reijou wa Ryuutei Heika wo Kouryaku-chuu

Jill Cervel, a noblewoman with magical abilities, trained extensively for battle to support her fiancé, Prince Gerald der Kratos. After he condemns her to death for uncovering one of his hidden truths, she prays for a second opportunity at a simple existence. Her wish appears to be granted, but with a condition—she must marry the Dragon Emperor, a future adversary of her kingdom. Though hesitant, Jill agrees to the union, which may alter the fate of her world.