As a fan of N, i also question whether he is the villain, Red Cry or not, despite being a fan i admit he's green. But then i remember he was actually cast in a lead role of a Psychological-Thriller "Interview" Musical twice (last year & last month,Oct.) he got good reviews for the role. In that role he plays Sinclair w/c has multiple personality disorder (5 personalities), i forgot the details of the personalities but one of them is a killer (?) and his alcoholic father. The reason why i'm 50/50 of him being a villain was also the fact that he accept this drama, right after this musical so who knows, after all this writer makes everyone suspicious in Achiara and the killer might just right in front of our nose, might also pulled of a red herring that's not actually a red herring.
So for me it's N or Kim SunAh for now, they are just too suspicious.
If this was a film or novel i would definitely watch/read this.. the poster and synopsis in enticing