I know best friends from the side of the light who discover the anti-hero's dark side normally meet this end, but… DAMN did the authors do Seon-uk dirty. This was one hell of a painful chapter.
And yet I gotta admit… it worked. Most authors of silly OP hero series don't know how to make a death matter. The pointless, almost accidental way Seon-uk died really drove home the point of how depraved criminals working within the institutions can get, and how much more it grates on us when those supposed to protect us do it. As someone who lives in a country where the police pull shit like this every day, I was gnashing my teeth typesetting this.
And I guess Jiyong's mental state will break from this for good. Not only did he fail to save someone else dear to him (the flashback to his mother's death was painful), it happened as an indirect consequence of his vigilantism. While one could argue that destroying this racket will save many other lives from death or ruin, the fact remains that Jiyong's track record so far is quite messy. And they aren't even out of the woods yet, Mr Bang is in the building, Gang-ok is injured and out of action for now (I don't think he's dead, the shots seem to have hit non-vital areas), Miryeo has the evidence but hasn't been able to leave the building yet, and might even meet the police goons on her way out.
This is gonna be ugly, and I'm starting to fear the big criminal won't be caught in the end.