Naruto: The Prince of Lust - Chapter 207 -

He was the continent’s strongest and most revered alchemist, Ye Zifeng. He was under one person and above millions. However, due to an unpredictable event, he had died. After his rebirth, he had become the supertrash of the Ye family and suffered disgrace. To make matters worse, he had an argument with his fiancé that led to the break off of his engagement. In this second life, he will work to change his own destiny. He vows to return to the peak of the world, trample on those who laughed at him and rewrite his legacy!

- Description from Novelupdates

This legend tells the tale of the protagonist, Kuroki summoned to protect the demon king from the hero.

Kuroki, unbeknownst to him, suddenly came to another world. He was summoned by the demon king, Modes. The territory which the demon king overrules was in the midst of being destroyed because of the hero. He had no choice but to bow before Kuroki.

“Please save us, Savior Dono!”

Kuroki nodded, deciding to save the demon king due to an unexpected turn of event.

The weak cry out with all their might, yet no one cares; The strong whisper softly, yet their words penetrate deeply into the heart. A Talent Tree ablaze with flames, every leaf bearing different spirit runes, Lu Ye, reduced to a mining slave after his sect was destroyed, used this to become a cultivator and stirred the winds of change in the Nine Provinces...

Yuan was born with an incurable illness that left him blind at a young age and crippled a few years later, rendering everything below his head useless. Deemed hopeless and irredeemable, his parents quickly gave up on him, and the world ignored him.