Conquest Of The Fallen: Dark Dominions - Chapter 313: The Gory Sabbath

Xia Yan passed through to the world of Bleach and became an eleven-year-old boy. He was rescued by Renji and Rukia in the Seireitei, and he was studying at Shin’ō Academy, and he was a student of the same class.
He is a top student of the Shin’ō Academy, and he is vying for strength by various teams. In the end, he has entered the first team of secret mobile maneuvers.
He will use punishment to kill every person who tries to threaten the martyrdom and protect his loved one.

- Description from Novelupdates

The mountain village boy accidentally got the fairy gourd, and he rose step by step to cultivate immortality and longevity.

Ripe elixir, mortal flow.

- Description from novelbuddy

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]