Fairy Tail: I Don't Want to Be the Guild Master - Chapter 465: Cathedral Bells

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

The mountain man, an immortal, roams the peak of Qingyun.In the furnace of Yin Yang, he refines, The Great Dao Path stirs within his heart.Luo Chen traverses through the Cultivation World, empowered with a Proficiency Panel. With pill refinement and Qi refinement, he steps towards the Path of Longevity.

Once an unsung slave; Yur’s existence was defined by blood, pain, and chains. That was until he stumbled into Zulmasharr, the realm of demons.In the depths of despair and agony, a near-death encounter unsealed the terrifying truth of his existence; he is no mere mortal. A cursed hybrid of human and demon; Yur’s survival was only possible through the bloody rebirth of his Ashkavaal bloodline and the awakening of his sinister cultivation system, Zul.With Zul, Yur can rear demons for rituals, harvest their power, and dominate the chaotic world around him. But freedom comes at a cost. As the incognizant successor to an ancient being, his every step is burdened by the weight of a destiny he never asked for. Yur craves only one thing: to stay free, unbound by demons and men. Yet his growing power and severed bloodline ignite the fascination of forces that would see him enslaved or slaughtered.Yur must steer through a world of demons where trust is a fault, survival is animus, and his very existence is a blemish. Blood will pour, flames will revolt, and demons... they kneel or die. But in the end, is freedom attainable for the bearer of a bloodline forged from blood and ash?Will Yur vanquish his fate or will it condemn him?

Two heroes of the game Legend of Heroes 2 who were rotten waters*.