You've probably seen some design of a prison before but let's talked about it anyway.
So, Greg is, at the moment, inside a temperory jail. Not a jail cell, but just temperory jail. Have you seen one of those?
Basically, it's a sharing jail that have private cell and it's looks like dorm but with..... You know what I mean.
I don't typicaly explain something well, so just search it on the internet. But if you don't want to, just think of a sharing dorm with multiple bedroom but change that room to jail bars. Yeah, like that.
Hell's Prison is no different.
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Shermen Faust
One of the guard in the prison. He's nothing special, and has no great power. His power involve his mouse nose. He can detect nearby food and enemy with his smelling. It's a great power IF you with someone in a team but he never had a partner, that's literally the reason why he never got a chance to the squad guard. His lack communication and short temper also some of the reasons why he still becoming a cell guard.
Yukihari Tamashita
An attorney with big ego. He will help people that he like but slip all people that he doesn't like.
He has mind power which grant him mind control ability, as well as memory seeking, mind alter, psycho changes and sexual changes.
He never been the most friendly with his client but he sure do justice to them if he like them enough.
Magnus Princeps
The short version intro would be the Hell's 32nd ruler, but the long version is:
He is currently the most charming ruler the Hell's ever has. He porpose himself to do judgement tasks and throughout his journey, he doing it well.
His father, the past ruler of Hell, was proud of him due to him finishing all task the his father can't finish.