MTL - The Roots of Manga - v3 Chapter 327 assassin and the world

It begins on the mountain.

With the glint of a knife, a flash of steel in the hands of a sworn brother. A betrayal.

Stabbed and pushed down the mountain, Zi Chen lied within the red-stained snow, left to die.

This is where it begins; he is given life by lightning,
baptized by thunder.

Those who had once betrayed him should all suffer in his cruel revenge.

- Description from Novelupdates

Hagoromo Gensou transmigrated to the Naruto world and, through his own efforts, became a prominent figure in the ninja world.Until one day, the newly appointed Five Kage teamed up and ambushed him immorally. It was only then that the system finally appeared, claiming it could help him rise to become the strongest in the ninja world.However...Just as he was about to confront the Five Kage head-on, Gensou silently looked at the first task issued by the system.[Quest: Ninja School Comeback Initiated! Please defeat your dead-last classmate, Uzumaki Naruto.]“System, do you know what year it is now?”[Year 60 of Konoha]“Right now, it's Year 2 of Konoha! Is there something wrong with this system?!”...Many years later, Gensou opened his eyes again, standing on the rooftop of the Chunin Exams building. Looking at the Third Hokage, who was ready for battle, he smirked slightly:“Although it's a few decades early, I finally made it.”[Raw: 火影：我都硬刚五影了，系统才来]

A 40-year-old man suddenly dies and is reincarnated in a world devastated by zombies—but instead of becoming a hero or a survivor, he wakes up as a zombie girl.

On the brink of destruction, I regained consciousness and found myself back in the past, 20 years ago. In order to have a peaceful retirement, I must prevent the impending doom.