The Cursed Prince's Strange Bride - Chapter 76 "Wake Up,"

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

Within the virtual world of “Avalon Online”, Finn, or otherwise known as “Echo” within the game, was one of its greatest players. After logging off from a long session, however, he notices something awry outside of his apartment.The streets were flooded with chaos, screams echo through the night, and hell is loot loose. Monsters from Avalon Online are running through the streets, wrecking havoc. In the midst of this hellish awakening, Finn is greeted with the one gift bestowed to humanity in this dark hour:[...Assessing life experience…][Assessment Complete][Name: Finn Thorne][Age: 20][Designated Class: Assassin][Starting Level: 5][A [Legacy System] has been bestowed to you for your accomplishments within Avalon.][Assimilation System Awakened.]In this twisted turn, as the world as it was once known is gone with the arrival of magic and monsters, the remnants of humanity must level up if they wish to survive.Finn is left in this dark, hopeless apocalypse, using his own experience from Avalon Online to best survive what seems to be an impossible task.

To correct the mistakes of his past, a young man is forced to narrow the space between science and witchcraft, as he ventures on a quest to save his world from complete destruction.

“Even if this universe is truly nothing more than a brutal bloody shadowy forest, we Cultivators will burn all that we have just to give off a single weak flickering spark in the darkness!

No matter how weak each spark is, how short-lived, how small… As long as the sparks flow unabated, then one day one of those sparks will light some tinder, and that tinder shall light some fallen branches, and those branches shall set ablaze each and every last tree of the forest!

In the end, even the smallest sparks will eventually set the shadowy forest ablaze, and illuminate the whole world!”

In a world teeming with cultivators, Li Yao, who makes his living collecting scrap metal, encounters the soul of a titan powerhouse from forty thousand years in the past.

- Description from novelupdates