Marvel: Umbrella Corporation - Chapter 4: For Your Own Good

He died in his first life, as an ordinary human inside an ordinary planet.

In his second life, he swore to live a life of supreme power, and so he did. He reached the apex and exterminated his enemies to oblivion.

Dying, he was reincarnated in a world which could use Chakra. He became The Overlord Of Every Being, Ruler Of 6 Universe.

Unfortunately, he died. Using a mysterious method, he was reincarnated once again inside the world of Tales of Demons and Gods.

What would you do if you could restart your life?

We do not belong to the light nor do we belong to the darkness, we walk the line in between.

There will be no people singing our praises or bards retelling our heroism but we will have pride in our work.

– Law of the Demon Hunter, Prologue

- Description from Novelupdates

A man who was once called the world’s strongest agent ended up becoming a teacher after his retirement, to train a new generation of agents. After many years of training his disciples, he was killed at the age of 60 by a secret organization’s ruse and was reincarnated in another world with his memories intact. Though he was surprised by the existence of magic and the strange species in that world, he quickly adapted to his condition as a newborn and took advantage of it. He acquired special magic and gained a massive amount of strength thanks to his rigorous discipline, in order to reach his goal: Resume his career as a teacher which he left halfway through in his previous life. This is the story of a man, who, based on the memories and the experiences of his previous life, became a teacher who travels through the world with his students.