MTL - Comprehensive Manga: a Journey Through the Supreme Being - Chapter 75

In the end of the world, the fittest survive.

Come back from rebirth, seize the opportunity, just want to survive in the hopeless end times.

Three months before Mu Nan returned to the apocalypse, he sold all his savings to accumulate supplies, hoarded everything he could hoard like a hamster, and then huddled in his own house and lived a low-key life, carefully waiting for the apocalypse to come step by step…

- Description from Novelupdates

Reach the peak of immortal cultivation and become able to run amok without fear! Use the power of martial arts to rule the world and defeat heroes! The weather changes at the whim and wave of a palm. He who cultivates both immortal techniques and martial arts, who could possibly defeat him! Xiao Chen is a shut-in who purchased a ‘Compendium of Cultivation’. Soon after, he crossed over into the Tianwu World, a world ruled by martial arts. He then refined pills, drew talismans, practiced formations, crafted weapons and cultivated the Azure Dragon Martial Soul that had not been seen for thousands of years. This is a story that tells of an exciting and magnificent legend!

Following a brutal and tortured death, a former assassin, known only by his codename Kuro, is given the opportunity to reincarnate in another world, a world with magic and monsters. Armed with an unrivaled healing factor and an inhumane pain threshold, Kuro opts to go for a reckless direct approach in this world instead of a stealthy and cautious one, and as a result, slowly gains attention bit by bit.

Having previously been a loner in his old life, he interacts and befriends people for the first time in his existence, however, his blunt nature also sees him making just as many enemies, both big and small. By combining his old assassin skills with the magic powers of this world, along with his high resistance to pain and rapid regeneration, he doesn't take long to establish himself as a formidable force in this world.

Initially, Kuro only faces minor threats, like weaker monsters and bandits. But before too long, the threats slowly but surely become more and more severe…from Zombies to a bloodthirsty empire to Vampires and Demons, and even divine beings…however, as the enemies he faces grow stronger, so does Kuro, gaining rare powers that have never or rarely ever been seen in this world…

What got summoned was the world’s strongest sociopath.