Hell's Handbook - Chapter 10: Understanding

I transmigrated into the gacha game I abandoned for 10 years.But, the state of the heroes I raised is strange.

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

Unexpectedly, Gol-D-Roger who was in his fifties had a teenage brother. But he was so weak.

Fortunately, at the age of sixteen, he actually found himself with a possession soul system.

He had attached to the master IP man, also to the White Phoenix and to Ge Nie with his strong ability of the Hundred Step Flying Sword.

If you think that he can only Purchase these? Then you’re wrong!

Pain, Itachi, Ichigo Kurosaki, as long as there is money, any soul can be Purchased.

- Description from Novelupdates

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

TL Description: Eat The World Tree is about a strange guy, who happens to be extremely curious and unable to stop himself from acting on his curiosity. The MC makes a slight mistake and travels to another world, and must fulfill specific quest or face varying levels of consequences (normally death).