The Do-Over Damsel Conquers the Dragon Emperor, Vol. 1 (manga)

Jill Cervel, the magically gifted daughter of a noble family, dedicated her life to training for war. It was all for her fiancé and one true love, Prince Gerald der Kratos… until he sentences her to death for discovering his dark secret! In her final moments, Jill wishes for another chance at a normal life. She just might get her wish, but there’s a catch—she has to propose to her kingdom’s future rival, the Dragon Emperor! It’s a reluctant vow for Jill, but it could end up changing the course of history…