MTL - Martial Arts: Just Finished the Patrol, the Beginning is Ruthless - Chapter 58

A man was transported to Ancient China and eventually became a servant of a declining household without a male heir. He utilized his wits and modern knowledge to help the household and eventually become trapped in the sea of political turmoils of the period.

- Description from Novelupdates

Luo Yi, a high school dropout in his original world, was isekai’d into the world of the Witcher 3. Starting out as a weak boy named Roy in the village of Kaer, Lower Posada, he was determined to grow stronger, no matter what it took. The first step toward becoming a legend was to kill. And his first kill was… a rooster. ‘You gain 1 EXP.’ Of course, Roy had his own cheat system like all the other isekai protagonists. His first step to becoming a legend started now…

In the past life, he was an aerodynamic engineer of a well-known company, and in this life, he is a college student of a famous school.

When the two identities are perfectly integrated, what sparks will appear.

His life experience is also slowly uncovering the mystery, whether he can beat the tycoons of this era, and whether he can stand at the peak of world business.

- Description from novelbuddy