The Extreme Alchemist of the Mighty Cauldron - Chapter 1930 - 2027: The Heaven-Defying Pill

A boy from 21st century Earth, met an accident and later was reborn in Naruto’s Ninja World.
He is born in Uchiha Family and becomes the useless brother of Itachi Uchiha and Sasuke Uchiha…. Let’s see how he changed the Naruto world.

- Description from Novelupdates

The whole world mutated. Mysterious resurrections happened in real life. The Tribulation descended.

war, blood, and betrayal carved him into something else. A legend. A killer. A mercenary whose name struck fear into both criminals and so-called heroes alike.But now, the world had changed. Lines blurred between right and wrong, between justice and vengeance. Should he step into the light, wear the mask of a hero, and fight for a cause greater than himself? Or should he embrace the darkness that had always been his home, a place where morality was just another illusion?“Don’t box me in with your shallow ideas of good and evil,” he muttered, his voice calm but edged with danger. “I do what I want, when I want.”The air was thick with tension as he moved like a shadow through the dimly lit room. The writer had no time to react—one moment, he was scribbling nonsense about legends and myths; the next, a cold barrel pressed against the back of his head.The figure smirked beneath his mask, eyes gleaming with something between amusement and menace.“You wanna write fiction?” he whispered. “Then let me show you how real legends are made.”A single gunshot shattered the silence.As the writer’s body slumped over the desk, the man holstered his weapon, stepping into the faint glow of a flickering neon light.“It’s that simple,” he said, his voice unwavering. “I’m Deathstroke.”

Enemy of the world, cursed by all, Kim Sungchul goes on a quest to prevent the ‘prophecy of the end’ from coming to pass.

But no matter how much he raised his strength, there were still some things he could not achieve with physical strength alone.

Resolving to obtain the power of magic, he goes into hiding to learn magic from his most hated of enemies, The Mages.