The Yu Brother's Case Book - Volume 1 Chapter 10.1

In the Abyss, all beings are imprisoned, struggling bitterly to survive. One day, in the eternally dark lower world, a young boy has a chance encounter and catches a glimpse of the upper worlds. He is fortunate to witness wonders beyond even the most beautiful dreams. Realizing there are worlds beyond his own, he refuses to settle for mediocrity and vows to ascend to the top step by step.

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

“Great Mr. Chen Yu, you were successfully elected as the leader of the human race last night. Is there anything you would like to say to the world?”Chen Yu, bewildered, woke up and hadn't even put on his clothes yet. He replied, “I have no idea, I just woke up...”

Follow Chen Ming as he accepts disciples, establishes a sect, and fights his way in a world that deems him a cannon fodder.
He goes against any common sense using his wits and novel knowhow to finish missions and arm himself against his cruel fate.