Instead of Checking In Regularly: I Hide And Cultivate In The Monster-quelling Tower And Become Invincible - Chapter 55: you are not human

Emperor Zi Yu used 5 strikes of his axe to split mountains and unify everyone underneath the heavens. He partitioned the land into 9 areas, thus establishing the Nine Cauldrons which eventually became known as the 9 prefectures.

He became a teacher at the best magic academy in the empire.
….For being mistaken for someone else.

Crossing to One Piece world, he became Roger’s younger brother.

A normal office worker, Toru Minasuki, was swallowed up by a dimensional fissure and reincarnated into a different world. Upon reincarnation, Toru was given a [skill board] by God. Make the most of it to acquire all the necessary skills! Even though he is an “inferior person,” he’ll make his way to the top!