Naruto: The Outsider's Resolve - Chapter 3.17 (076):

In a world where life energy fuels martial prowess, Shen Yifan, with a mere mortal lifespan of a hundred years, finds solace in slaying demons to extend his own vitality. Amidst the chaos of a realm teeming with malevolence, he brandishes his blade, striking terror into the hearts of creatures who have roamed the earth for centuries! Yet, amidst his valiant exploits, Shen Yifan sometimes ponders, why does his lifespan seem to dwindle faster with each use of his powers? Sheathing his sword, he gazes skyward, hearing tales of the divine palace in the heavens, where immortal beings dwell, having weathered endless eons. Embarking on a celestial journey, he seeks to beseech the gods for a loan of a million years, to pave his path towards eternal life.

In childhood, they were neighbors. Xie Zhen always bullied Li Yu.

—WSA 2025 ENTRY—The weakest loser they mocked for years wasn’t at all weak—he was a god in disguise, with the power to bring the world to its knees.“I want you to teach him humanity, so he who feels NOTHING but rage can at least learn morality”“And you trust a Demon to do that?”Seiya dreamed of becoming a hero, one of those legendary warriors everyone worships. But his Awakening failed, leaving him powerless and humiliated—a target for cruelty.Locked away and tormented by those he trusted, his suffering revealed the truth of his origin: he wasn’t just human.Unleashing powers that defy the laws of the world, such as his All-Seeing eyes—capable of negating time, absorbing skills used against him and granting him 360° vision.Seiya rises from the shadows, no longer a punching bag but a force that terrifies demons, monsters, and humans alike.Hero or villain? It doesn’t matter. He’s done obeying, done breaking for anyone.Now, they beg for mercy from the god they tried to crush. Seiya’s only question: should he grant it?Brace yourself for a journey of chaos, revenge, and the rise of an unstoppable power.Seiya doesn’t need your approval—he’s taking the world, one broken rule at a time.————————————————————Yes! He does turn to a cold villain and loses all emotion except rage but the process leading up to it might drag a little__stick around longer and you won’t regret it.Read the prologue next after this so you understand the world settings.

That lonesome night as he lays dying in the hospital, fearing of death and desiring the taste of life, his mind became unprecedentedly complex with mixed emotions.

Myasthenia gravis — an incurable disease where one’s muscle slowly degenerated until the day when one can no longer move and only tears may flow.

“Is this… dying?”

When he opened his eyes again, he had crossed over into the body of a two months old infant, right in the middle of an assassination attempt.

He was born as the illegitimate son of a noble. His name was Fan Xian; and with that name came the burden of deep political secrets and the legacy of his mother.

He understood; to survive, he needed unparalleled strength, money and political power.

To a new world with the luxury of a new life, so named; Celebrating the Remaining Life.

- Description from Novelupdates