The Immortal Seeker: Legend of Bronze Mirror - Chapter 5: Soul Stabilization

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 cycle of life is not infinite—except, perhaps, for Elijah.At 122 years old, Elijah lived a long and successful life—until he woke up as someone entirely new. Now, an anomaly in a mysterious kingdom sustained by magic, he faces questions about his place in a world that doesn't defy the laws of nature, but take them to an entirely new level.For over six millennia, this isolated realm of 300,000 citizens has thrived, its survival bound to the magic that nurtures its air, water, and food. Yet, some whisper that a kingdom refusing to expand is doomed to fall. How, then, has this kingdom endured?As Elijah uncovers ancient secrets, dives into treacherous cave systems, and grapples with the fatal flaws of magic, he learns the truth about existence itself—forces that shaped the cosmos. New alliances rise to confront an ancient plague, and the kingdom's delicate balance teeters on the edge of collapse.In this world, the vibrant hues of freedom and potential are mere illusions, like sunlight filtered through stained glass. Elijah must decide whether to shatter the illusion—or embrace it.————This novel goes into great detail about the ways of the people and how it will differ from the suspected outside world. What seems like a population of people who do not have much knowledge, show how they found their way by “feeling”, or by anecdotal(personal) evidence.

“Now that I’m back, I won’t allow my loved ones to die again!”

The Shadow Labyrinth – the most catastrophic existence humanity has faced in history.

Desir Arman is one of the six remaining survivors of mankind.

The six attempted to clear the final level of the labyrinth but ultimately failed, and the world came to an end.

However – when Desir thought he would meet his demise, what is revealed before him is the world… thirteen years ago?!

Desir is returned to the past, back to the time when he enrolled at the nation’s finest magic academy – Havrion. He is reunited with his precious friends, and is prepared to change the past to save the world and his loved ones…!

Three years remaining before the emergence of the Shadow World!

Change the past and gather powerful comrades to save mankind!

Crossing into the world of Naruto, and acquiring the One Piece system, with all the powers of the world of One Piece, swordsmanship, devil fruit, domineering.

-Do you think that your fire is very powerful? I have the burning fruit.

-Do you think that your thunder is very powerful? I have a thundering fruit.

-Do you think that your otter is very powerful? I have the frozen fruit.

-Did you said you want to die? Don’t worry, I also have a nickname: Death Doctor.

- Description from Novelupdates