@Rikuhearts79  

My unserious guess is the same, Jo Dan, just because.  No one is paying any attention to him.  They set him up to be a computer genius yet he finds out very little. We have 0 motive but it would be entertaining.

I'm just at episode 2, but I can say that:

- In episode 1 the strangest one was the student bumping into Joo Hyun and the teacher (the one sending message to "start" something - Now that I've seen more, also the Red Tumbler and the reaction of the student when Min was trying to keep the runaway still... I don't know, I think Ji Hoon (I'm not sure about his name) is definitely involved. 

- In episode 2, isn't it Joo Hyun in one of the photos of Seok Joo? Protesting, in front of the prison. Also, she knows what Seok Joo said in court, so I think she is involved somehow (maybe just a fangirl or seeking revenge)

- Finally, the prison guard who tries to befriend Moo chan was suspicious.

Okay, I don't know yet xD

Tbh, the guess board is pretty much. I always suspected the homeroom teacher but I'm sure he isn't Gaetal. But I'm very much interested in that police hacker, something is definitely suspicious about him. If the quiet school boy and his grandmother are also fans, I don't know what to think again.

Lee Min Soo is definitely among those behind the mask, so you guess may be true.