One true KING: Magnificient monarch

It's the story of an ordinary man becoming a knight. It's the story of an unordinary monarch protecting his people. It's the story of a man that returned to save his continent. Experience points acquired!? 2nd Title: From the lowest foot soldier to the king title

Richard, the ambitious third son of the House of York, believes he is cursed, damned from birth to eternal darkness. But is it truly fate that sets him on the path to personal destruction? Or his own tormented longings? Based on an early draft of Shakespeare’s Richard III, Aya Kanno's dark fantasy finds the man who could be king standing between worlds, between classes, between good and evil.

I died while I was reading hate comments on my novel. I was already in shock over my death, but some 'Grim Reaper' appeared and told me that being a bad writer was a sin. To atone and make it into heaven, I was told I needed to survive past the ending in one of my novels. And so, I entered the novel ... "Damn it all!! Why did this have to happen to me?!" By all misfortune, the character I possesed was the Demon Prince, a character with no combat abilities—who dies at the very start of the story!

Ghislain Perdium, the Mercenary King and one of the continent’s top seven, started a great war in an attempt to avenge his fallen family.
His plans of revenge were going smoothly until he was slain by Idun, who he had never expected to make an appearance. Ghislain thought he died, but he woke up as a younger version of himself from before the fall of his household.
With this second chance, he decided to fix all the wrong pieces of the puzzle and avoid making the same mistakes he did in his past

Read manhwa Eternally Regressing Knight
You’re a genius.” Those words he heard as a child were poison.
Encrid dreamed of becoming a knight, but he soon realized it was futile. “You want to live by the sword with that level of skill?” Some laughed at him.
“Just give up.” Some advised him against it. Despite that, his dream remained steadfast. He slept less, ran more, and trained harder.
One day, he died, having been stabbed in the neck. Encrid opened his eyes again to “today’s” morning.