The girl bum killed wasnt the girl that bullied him, Bum was driven to kill because he thought about the girl that bullied him. Also bum has info against sangwoo like his parents murder that he can use against him and sangwoo basically trapped the girl in his house making him at fault too because he also helped climb and bury her. Sangwoo cant turn in bum either, because bum has scars and was physically abused by sangwoo.
Your theory is mostly flawed.
Uh, it was the girl that turned her back on Bum at school. >_>; He also had personal grudge on her since she entered his life but also left him. He told her himself before began stabbing her ¯_(ツ)_/¯
But yeah, that theory in the first comment is a no no since Bum has the most severe scars while Sangwhoo is unscathed-
I get what you mean but when bum was at the police station he could've told the truth about sangwoo but he didn't (which is probably because he thought he was better of with sangwoo than his uncle). Bum is quite a lot in love with sangwoo and gets willingly manipulated by him but can't see it because he thinks that sangwoo loves him. So it wouldn't be surprising if he let sangwoo point everything on him. But yeah my theory is flawed I should've reread everything before writing it.#－.－)
No the girl that was killed isn’t the same girl that Bum obsessed over and went to school with. It’s very clear that he is projecting the image of that girl onto the victim that Sangwoo had been playing with. He let the emotions that had been within him out and he took it out in her. It’s pretty obvious
So I've always had this theory that sangwoo is eventually going to turn on bum. So hear me out. First of all, he made bum kill the girl (which wasn't any girl, it was someone he knew and someone that hurt him (bullying) so therefore that was a motive). If asked about it by the police bum would agree to that because it's true is quite of the passive type so probably wouldn't lie about that. Then, when they went to burry her the lady saw Bum and could maybe recognize the dead girl ( yeah I know sangwoo was seen too but this motgerfu- got away with killing his own damn parents so I think he can get away with that.) also there was a couple that saw them too. And (if I'm not mistaken) bum dug (at least mostly) the place where she was buried so then again he can't deny that if questionned. Bum also took a bite of the apple that sangwoo left where she was buried. When people were looking for her he mentioned bum, he said that's the last person that knew her whereabouts. And now he kinda wants to make bum the sole responsible for her death . So I have two theories either when bum tries to leave or expose him he'll blackmail him because bum killed that girl. Or he will blame everything on bum saying that many of his own crimes were bums and he got manipulated by bum because he loved him and so helped him in his murders. Also in the second one yes he'll get punished but less because first of all he was helping bum not actually killing him and was in an abusive relationship from bum and since the officers have a nice image of him they'll give testimonies that he's actually nice. That since his parents died he was lonely and when he found bum it made him (IDK) complete (I guess?) so got manipulated by bum. Also bum was that creepy guy in front of sangwoo's house trying to get in, they didn't really like him from the start so they'll be less inclined so believe him. Also their police force are shitty they'll probably solve it by them selves rather than this going to court and stuff. But that's just a theory
A game theory....