"No matter how many times I die, I promise that I’ll save you. With this..."

The Seventh Prince of the Amalthea Empire, Reidrick von Amalthea, laughed.

He had just received a report that his current political enemy was killed, though at the cost of the life of his body double, Ted Shinel. However, that brief moment of celebration had created a gap.

"Your role is finally over."

The last thing Reidrick saw before dying was the face of his body double, Ted, who was supposed to have died in his place.

There existed a power different from martial arts and magic—it was a Miracle (Gift).
Ted was also granted one such Miracle (Gift).

That ability was the [Extra Life System]. So long as he had lives remaining, he could revive as many times as he wanted—a power beyond comprehension.

Ted had hidden his special power, enduring various hardships, all for an opportunity…
For the sake of killing Tithi Yuguwi, who had killed his friends from his hometown, and for the sake of his sister, Claire, who had been taken by the Empire.

He swore vengeance against the Empire, and to do that, Ted took on the prince's role—all to usurp the throne.

To make full use of his [Extra Life System]… to seize the throne

(Source: MangaUpdates)