My Passive Skills are Invincible! - Chapter 295 - Return to Where You Came From.

I have experienced all the eight sufferings of this world.

I do not ask for nirvana, but for you.

Wild and hard-to-tame demon (gong) x cold, ascetic and childish immortal (shou)

- Description from Novelupdates

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…

When gods gather, lightning will strike and the earth will move. Immortals! Which of the numerous way to immortality should one follow? Immortals are hard to seek, but why should immortals hide? Heaven has no mercy, but humans have emotions, and these emotions hinder the road to longevity!

Train the inner self to stay calm, train the external body to be resistant, then cross the three continents and four seas alone, and fight valiantly with demons and devils! With the heavenly baton in hand, raid the devils and demons without any resistance! Take one step to cross nine stars and chase the sword in the dreams! Traverse a thousand li of river and mountains in a single day! The exceptional beings do not mix with the ordinary! Within the universe, where can one find an obstacle! Moving like a dragon, with talent like a phoenix! The heavenly Daos and stars will guide one’s way!

- Description from Novelupdates

After the ‘100-Year War’ between the Necromancers and Priests, an all-time genius who’ll shake the power structure was born. “Am I a rare case or something? Do I have talent?” A potential beyond all imagination. He obtained his father’s undead army and entered the great Necromancer school of Kizen that divided the continent. Geniuses are geniuses, even when gathered among the elites. The research community was flipped on its head by the appearance of a new case. Professors wouldn’t leave him be alone, wanting to make him study directly under them. Officials from all over the kingdom and heads of organizations fidgeted over whether to scout him. “Professor! When can I make a Lich?” “Gimme a break. How talented are you? You’re crossing the line, honestly.” A genius among geniuses had appeared.