I Became a Genius Commander at the Academy - Chapter 26: Reclaim The Territory (5)

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]

Travel to the game world.

Matthew found that there seemed to be a little problem with his system.

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“Occupation: Necromancer

Task: plant trees

Target: 1000 trees

Reward: Summoned item ‘Bone Dragon’ & a lot of EXP”

…

In this way, a necromancer who respected the way of balance more than the druid was born.

…

- Description from novelbuddy

This world has Fox Fairies, River Gods, Water Monsters, Great Demons and Cultivators who seek immortality.

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.