Class Change for All: I Became a Jailor of the Nine Gates from the Start

(Nine Gates of Jail + Everyone Gets a Class + Power Fantasy)

[Boss, your class is definitely strong, but it takes too much skill to use. Can you recommend something simple and powerful? Sure thing, bro. There are plenty of powerful classes, and there isn't just one as strong as mine. I've got nine classes this powerful!]

A young man from Earth transmigrates to a world where spiritual qi revival has taken place and everyone gets a class. By chance, he obtains the Nine Gates of Jail System and changes class to one of the Nine Gates of Jail professions. Now he will write a legend for the Nine Gates of Jail in this new world!