The Reincarnated Assassin is a Genius Swordsman - Chapter 686

The constant mission is getting redemption.

Shuttle though various worlds to become a variety of scum men, do a little whitewashing and become a good man in the eyes of everyone.

Redeem those who are miserable, and let them live a happy life.

- Description from Novelupdates

A decision can destroy the sun, moon and stars. A finger can kill the Heavenly Overlord. While chatting, the Heaven and ten worlds can be annihilated.

A poor little kid walks out from a remote mountain area while holding the Nine Dragons and the Incredible Cauldron. With a control over the time and space eternally, he embarks on the Path to God where he defies the odds of the boundless universe gaudily by fighting against royalty and clashing with the legendary generation.

- Description from Novelupdates

They call him Ghost.A name whispered in fear across warzones, black markets, and underworld circles.To the world, he's a phantom—a faceless mercenary who leaves no trace but bodies in his wake.To his enemies, he’s a death sentence.To his brothers-in-arms in Graveyard, he’s family.But to himself... he's a haunted man searching for a past stolen in gunfire and smoke.After a flawless mission deep in the Eastern Province, Ghost returns to the hidden forest base he's called home for sixteen years. Yet the victory is short-lived. His foster father, the commander delivers an unexpected order:“That was your last mission.”Now, Ghost—real name Miles Sterling—must step out of the shadows of war and into a world he’s never known. Guided only by a scarred letter, a fading memory, and the voice of a woman he hasn’t seen since the day everything was taken from him.But war forged more than his body and name.Behind the mask, behind the scars, Miles has another secret.One he’s kept hidden even from his brothers in arms.He’s not just a weapon.He’s a ghost with a fortune—a hidden empire he built in silence, across borders and black markets, forged in strategy and blood.A man of many names, and many shadows.Beneath the bullets, tattoos, and silence lies a truth buried in ashes.And Ghost is about to dig it up—one letter, one enemy, one memory at a time.

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.