I'm a duchess who's gone back in time, but I became the strongest hero thanks to the Demon Lord's cheat abilities!?

In a world ruined by the overwhelming power of the Demon King without the appearance of a hero, a beautiful man appeared before Lady Elfrote, who was in the depths of despair. He said, "Time will soon rewind, just as it has in the past. You will be the hero," he said, and gave Elfrote power. When Elfrote wakes up, she finds herself in the world of...... five years ago! Though she thinks everything may have all been a dream, Elfrote stands up to prevent the tragedy from repeating itself!

(Source: AlphaPolis, translated)