My Slayer System: Rise to Supremacy - Chapter 38: Grinding time

At 18, Alex Kain is whisked away to Eryndor, a game-like realm where he gains 'Skill Synthesis', a talent to fuse skills into godlike powers. Battling monsters and conquering dungeons, he builds a harem of strong women drawn to his might and charm. With the power to return to Earth bearing incredible resources, Alex faces a growing threat that endangers both worlds in this epic of adventure, romance, and ambition.

For Chen Cheng, thirty means interest—the interest rate.From 3,000, to 100,000, to a million, to ten million, and then to over a hundred million...An ever-increasing amount of principal, an endless stream of interest.With money generating money, compounded interest calculations made Chen Cheng exclaim:This money can't be spent! Absolutely can't be spent! For a lifetime, I can't finish spending it!

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

Enigmatic hands, spectral frame, and one cunning strike just like the swing of the Grim Reaper. The Supreme Assassin takes on the mystical world, and how his legendary tales sets off, progressively ascending the altar to becoming the best.

- Description from Novelupdates

The protagonist is an accidental time traveler - he didn't wait, didn't guess, only dreamed, but ended up in history, which he didn't pay much attention to. He was just lucky with his lineage.Ryo is a new member of the Nara clan, from the Uzumaki lineage on his father's side, and it so happened that he was born not at the beginning of the known plot, but more than three decades and two world wars later. Now he has to figure out how to get out of this situation however he can.