Supreme Emperor of Swords - Chapter 34 “Taixuan Sword-seeking Scripture”

Stealing Heroine from Protagonist with SystemWARNING MATURE CONTENT!!!!!R-18

Shuu is a member of the literary club that can’t write. One day, he gets a mysterious message on his phone from a girl called Eina, and from that impulsive contact, they begin to exchange messages. They talk of things like their shared interest in novels and grow close. However, when they try and meet, they discover a shocking truth. Eina lives… not in the present, but five years in the past! How will their love develop, parted by five years of nights…!?

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

“The Demon Lords are bringers of destruction, and among them, I am the strongest.”The Demon King has fallen, slain by the Hero in a battle that shook the heavens.After this, humanity knew a long era of peace and prosperity, with the hero now at the top of the world.Fifty years after the battle, the demon race is resurfacing, but now with the throne empty, they must fight for the emergence of the new Demon King. Meanwhile, the humans are preparing for the rise of the next hero who will oppose their archenemies.Born as a mere stable boy in a lower-class noble household, Bel has lived his life tending to the noble gardens, pruning roses for banquets he would never attend. He is nothing more than a lowly servant in a world ruled by noble bloodlines and magic.However, his fate changes when a demon attack devastates the household. As flames consume the estate, Bel is about to be executed in front of his master when their leader, a great demon, recognizes him as a member of a powerful species of monsters that had disappeared before the ascent of the previous Demon King.She calls him by his true name, awakening his true blood.The demon, intrigued by this discovery, decides to spare him out of curiosity and pity. Having learned about Bel’s true nature, his master, rather than executing him, chooses instead to bring him into the heart of his household, seeing in him an opportunity to elevate his family’s standing by binding a powerful being to his service.But power cannot be shackled forever, and among them, the one in Bel's blood is the most dangerous.