MTL - Number One Player of Time and Space - ~ asshole, cunning old man

Kurono Maou is a high school student who is sensitive of his sharp eyes and bad expression. No girlfriend but gifted with friends in his own way, he had been living a peaceful life.

A college student, accidentally reborn into the world of Naruto, becomes a member of Uchiha who is destined to be exterminated.

In this cruel ninja world, in the face of endless wars and exclusion from the village, what will Uchiha Qing do?

PS: Later in the book, the protagonist will develop a system of immortal cultivation. Cultivating Immortals in the Ninja World, have you seen it?

- Description from novelbuddy

I am the sword.
Killing a man amidst a thousand miles, no one dares take ten steps.
Killing a man amidst a thousand miles, no one can take ten steps.
Killing a man amidst a thousand miles, ten steps? Not possible!
I am the sword, the sword is me,
On the path towards heaven, each shall wield their own.

I have given up power that can make the strongest of men tremble. I bore scars very few can imagine; loved women, very few had the gall to talk; and tread paths with chaosfiends.

“And I'm still standing.”

- - -

Gale was summoned into a mysterious world of magic and monsters for no particular reason. Thrown into squabbles of beings vastly higher than him, Gale strived to make a place for himself in the vain dream of immortality and a better world.

That was six years ago.

Beaten and battered from years of brutal war, Gale finally had enough and resolved to start over a new peaceful life in a totally unremarkable town with his trustworthy companion, Vale. Give up the weapon of slaughter and take up a hoe? That seemed like a fine deal to him.

Unfortunately, the valley wasn't as unremarkable as he thought it to be. Dictatorial governing bodies, suspicious practitioners, an exceedingly unwelcoming guest, and a secret that would change the entire world, all impeded his peaceful life. Gale will need all his mental stability to keep his temper in check, lest he brutalises his way out of trouble. Again.