Itai no wa Iya nanode Bōgyo-Ryoku ni Kyokufuri Shitai to Omoimasu - Chapter 445

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.

In an era when the power of Fire Magic was considered to have reached its limit, one girl began researching nuclear fusion.

The eldest daughter of the Li family is beautiful and sassy, ​​she took space materials to flee famine, and after going through many difficulties in war, disease and epidemic, she united with her family to regain the glory and harvested a beautiful boy.

- Description from novelbuddy

Leo awakens in a world he doesn’t recognize, with no memory of who he is or why he’s there. All he knows is that survival isn’t just a necessity—it’s his only chance to uncover the truth.Thrown into a brutal test for assassins on a hostile alien planet, Leo quickly discovers an extraordinary instinct for combat and evasion—abilities that feel second nature, yet remain a mystery even to him.But as the blood-soaked trials unfold, whispers of his lineage begin to surface. In a universe where gods are eternal and invincible, Leo carries the blood of the one being who defied that rule: the Timeless Assassin, a legend feared by mortals and deities alike.Now, hunted for what he represents and burdened by a legacy he can’t yet comprehend, Leo must forge his path through a deadly labyrinth of enemies, alliances, and cosmic conspiracies—all while piecing together the fragments of his forgotten past.For in the shadows of his fractured identity lies a truth that could shake the heavens themselves.