Ok so I after seeing what it looks like from the stalkers point of view when Jinha and Hyunjoon visited flowiz (chapter 24 page 14) I noticed he is looking at them from behind a man and a woman. So I went back to the chapter where they actually went to flowiz (chapter 11 page 10) and you can see that the that the person standing behind that man and woman in the middle is the guy with the glasses. I don't know if I'm looking to much into this but it seems like it cant be Lim Seo-il.
Possible Spoiler of who the stalker is
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Ok so I after seeing what it looks like from the stalkers point of view when Jinha and Hyunjoon visited flowiz (chapter 24 page 14) I noticed he is looking at them from behind a man and a woman. So I went back to the chapter where they actually went to flowiz (chapter 11 page 10) and you can see that the that the person standing behind that man and woman in the middle is the guy with the glasses. I don't know if I'm looking to much into this but it seems like it cant be Lim Seo-il.