Forgotten Title An underground novel I don't remember the name

So it's a novel I read a couple years back, basically the MC joins a mafia or underground organization, I forgot the exact details, but he was a normal person that just joined by chance and he uses his brains to rise through the ranks... sorry my memory is a bit fuzzy, but I think there was something like underground in the title. Please help me fellow readers!

 

The Evil Organization recruitment Ad! nvm I found it XD

 

That was a pretty good novel translated by yoraikun if I remember correctly