The Laws of Cultivation: Qi = MC^2 - Chapter 54Book 2: : Judgement

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.

The unparalleled Demon King Ye Xuan, who was able to heal the death or the living alike and holder of the medicine Holy Scripture, was betrayed and killed by his fellow Demon Kings. But he reincarnated into the body of Ye Xuan, the prodigal son of the Ye family and vowed to himself that he would return to his peak and take back everything that belonged to him!

- Description from Novelupdates

Su Xiao is a cold-blooded teenager who’s seeking vengeance for the death of his family, yet things ended up badly for him.

As he was taking his last breaths, he heard a voice calling him from dimensions, it was a strange system reaching him, asking him if he wanted to be saved, to be Reincarnated.

He just needed to accept a contract, Su Xiao didn’t have any choice but to do so, but he didn’t know what he signed up for!!

Traveling through worlds, doing extremely dangerous missions, collecting special items, leveling up, and even killing Protagonists…

But Su Xiao wasn’t any ordinary Contractor, Su Xiao was a Hunter!

The MC crosses over to: One Piece, Tokyo Ghoul, Naruto, Fullmetal Alchemist, Attack on Titans…

- Description from Novelupdates

A Wicked Witch, trailed by vengeful spirits and curses.“Hey, Tin Can! Did I not tell you to stop causing trouble?!”A Courageous Lion, descended from the bloodline of a hero.“Uh, no matter what, this seems like a bit much, no? Huh? Whatever doesn’t kill you only makes you stronger? Um, Sir Knight? Sir Knight!?”A Scarecrow, sealed away for pursuing the taboo.“Despite appearances, I’m quite capable from the shoulders up. Below that, you say? Let’s see, if I had to give a cold self-assessment… perhaps an emergency shield?”A Solitary Tin Knight, forever barred from human warmth.[The ‘Tin Knight’ urges everyone to initiate the boss battle, saying the cut scene is over!]This is a cruel, fairytale-like adventure story told by twisted protagonists.…Maybe!