Yarinaoshi Reijou wa Ryuutei Heika o Kouryakuchuu

Jill Savelle—fiancée of the crown prince Gerald de Kleitos and known as the "Lady Goddess of War"—is being hunted down by the same country she swore to protect. Betrayed by her betrothed, she is framed as a traitor and imprisoned. In her last moments, Jill is filled with regret, but just as death approaches, she awakens six years in the past. This time, she will not be a mere pawn.
Now as a 10-year-old girl, Jill resolves to escape her imminent engagement to the prince. To this end, she jokingly professes her love to the 19-year-old dragon emperor Hades Theos Rave, who will one day stain the land in blood due to madness. But against all expectations, he accepts!
In contrast to the tyrant from Jill's memories, the Hades of this time is a kind albeit unfortunate emperor. Can Jill prevent Hades from descending down the same dark, villainous road, or is he bound to an inevitable future?