Holy Emperor's Grandson is a Necromancer - Chapter 15: 011. Imperial Prince is Hunting a Witch -4 (Part One)

After an unexpected accident, An Luo was reborn as the young master of a business family. Even as his grandfather’s favored grandson, he seems to only be a cannon fodder in the brothers’ struggle to seize power. However, the most frightening thing is… the strange emotions that flicker in his little brother’s eyes as he looks at him. At that moment, overwhelmed by his brother, An Luo angrily thought: Could it be that he is doomed to never escape this vicious cycle of “brotherly love”?

An Luo(frowning): After rebirth, I don’t want to be together with some strange person.

Someone(suddenly appearing in the back, smiling): What did older brother just say?

An Luo: …Nothing.

- Description from Novelupdates

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.

Kurogami Ichiro was desperate because he couldn’t achieve what he wanted when he once started his martial arts path at age of 8!