Hmmm… is Seon-uk finally becoming relevant? That close-up on his nape last chapter as Jiyong was leaving the room, the one before that when he was listening into Jiyong's interrogation, and now his brief hesitation before answering "I don't know"… it's subtle but it's there. Does he suspect something, and if so, how? But frankly, Jiyong had no business asking Seon-uk, who knows nothing, about where in the building Yeong-il had been last: that's clearly something an interested party would ask.
I don't know how I feel about Gang Ok's behaviour. I can't say he's manipulating Jiyong: the things he's said are what any friend (brushing over the fact that normal friends wouldn't encourage you to be a bloodthirsty vigilante) would say to comfort someone who's having a guilt-ridden breakdown. And he isn't even wrong: Jiyong isn't to blame for Yeong-il's recklessness, or Jaehyeop's villainy, at a personal level. Like I said in the first post, Jiyong can be faulted for the morality of his general approach, but not for particular instances of violence.
So, while I think Gang Ok does treasure Jiyong as the closest thing to a friend, and Jiyong has begun reciprocating, it's not a healthy friendship at all, and Gang Ok seems to take relish in seeing Jiyong descend even more in the moral quagmire. (His dancing with joy in the parking lot was hilarious, kid must've been traumatised.)
An interesting point in this chapter is that for the first time, vigilantism has been validated as the only choice against "those standing above the law". Jiyong tried his method of getting the villain judged and acquitted before bringing the hammer of vigilante justice on them, but realised the villain wouldn't even wait to be judged. Now the gloves are completely off. We're heading into one hell of a climax.
One more thing: if anyone thinks Jiyong is losing it from that "everything is working out perfectly" and the maniac smile, I'll point out that this is exactly what happened in the first chapter: he was positively elated that his mother's murderer had remained scum. He is crazy now, but he was just as crazy as the story started. He actually prefers it when his prey isn't repentant or is even worse than he thought.