One Piece: The Devil Marine from Impel Down

[Impel Down + Nearly Invincible + Comedy + Unhinged Madness + Ruthless and Cruel]

Sanos transmigrated into Impel Down in the world of pirates and awakened a System.

As long as he punished someone, he could gain their physique, talents, insight, and racial traits!

To gain power, Sanos began ruthlessly punishing prisoners in this underwater prison.

Before long, he became the most terrifying legend in Impel Down: the devilish punisher from hell.

Roger, the Golden Lion, Bullet... Sanos punished every big shot in Impel Down.

A few years later, Sanos sat in the position of Impel Down's warden. From top to bottom, inside and out, everyone in Impel Down, whether guard or prisoner, bowed before him.

I, the King of Impel Down, am Sanos!

(Due to various factors, this story will end after the Impel Down arc is completed. However, the Impel Down storyline will be complete. Anyone who likes Impel Down is welcome to give it a read.)