MTL - Harue Kagetsu - Chapter 128

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.

Jack Somnus was a mid-wealth professor of economics and a trading advisor for the powerful Johnson family. But after years of working for the Johnsons, he was abandoned without a word. He was laid off without as much as a severence package. Jack’s life got worse when he lost his wife. Depressed and alone, he got into an unfortunate accident. Instead of dying, he travels back in time to his teenage years. Now, Jack has a second chance to live the life he always wanted. He wants to be the one who controls, not the one being controlled. But his time travel hides a deeper secret, one that might throw him for a loop. [WARNING: CONTAINS EXPLICIT EROTIC SCENES]

An Individual from Earth finds themselves in the Shinobi World, equipped with a Scientific System. From that moment, he delved into scientific research far ahead of its time.