A series of short stories set in the Mob Psycho 100 universe, all done by other authors.

Do you or someone you know need an exorcist who works cheap? Reigen's your guy! What's his secret to busting ghosts while keeping prices low? Well, first, he's a fraud, and second, he pays the guy who's got the real psychic power—his student assistant Shigeo—less than minimum wage. Shigeo is an awkward but kind boy whose urge to help others and get along with them is bound up with the mental safety locks he's placed on his own emotions. Reigen knows he needs to exploit Shigeo to stay in business, yet for better or worse he's also his mentor and counselor. And he also knows whenever the normally repressed kid's emotions reach level 100, it may unleash more psychic energy than either of them can handle!
 
(Source: Dark Horse)
 
Note: Includes 12 extra chapters.

Tags