One Piece: Unreal Adventure - Chapter 28: Yes, it’s me, Mario!

In the Solarian Empire, people were divided by their blood. The nobles enjoyed their life in wealth, with fine wine and amazing food. They reigned supreme over the commoners. The only reason they were able to do this was that they had knowledge of the most powerful force in the world - magic. The nobles controlled their knowledge from easily going to commoners, making it harder for them to learn magic.

Leo, a young orphan in Solaria, had an incredibly powerful affinity for magic. He didn't even know about it because he could never learn magic- he was too poor to try and learn from any magic academies. He was just trying to survive the streets of Solhaven until he found the lost tome of the Arcane Emperor.

"I can beat a 7th Circle Mage."

"Wow! You must have trained for many decades. How old are you?"

"17."

"..."

The world was going to be turned upside down.

A normal office worker, Toru Minasuki, was swallowed up by a dimensional fissure and reincarnated into a different world. Upon reincarnation, Toru was given a [skill board] by God. Make the most of it to acquire all the necessary skills! Even though he is an “inferior person,” he’ll make his way to the top!

Standing before you are:

Guardian and patron of darkness,

Disruptors and Reshapers of Order,

creator and persecutor of licking dogs,

The tea master, the goddess of the dark night, the nightmares and gravediggers of the gods,

The true ancestor of blood – Charlotte de Castel.

With madness, with blood, with curse, with destruction.

This is a legend belonging to the blood family…

- Description from novelbuddy

A man who was once called the world strongest agent ended up becoming a teacher after his retirement to train the new generation of agents. After many years of training his disciples, he is killed at the age of 60 by the ploy of a secret organization and was reincarnated in another world with all his past memories.Though he was surprised by the magic and the strange species of that world, he adapted very fast 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 tight 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 new students.