Don't Panic, I Have a Government Job in the Underworld

I'm the unlucky guy who was bullied into paralysis by a rich, influential school bully. No one listened when I reported it, and my life was ruined. Just when I wanted to die more than anything, the Underworld sent me a job offer: become their temporary worker in the human world, specializing in dealing with the bastards the law can't touch. Now, I've gone from a helpless wreck waiting to die to their living King of Hell. The ones who sent me to hell back then? Now I'll send them in first.