
Well the teacher kinda deserves it tbh. He knows Heonjae is slow and he's taken advantage of it. He even stole his money. He know that if he gives him affection, Heonjae would do better. And if Heonjae does better, he'd win. And when he wins, he gets money. So all the caring and attention was deliberate and planned.
The teacher may have not groomed Heonjae, but fucking asshole manipulated him. So yeah, well deserved death

He was not a good person, that's true but he deserved to get beat up, not tortured. I'm with you, when it comes to ppl getting revenge on evil manipulators. From what I remember of them reading Heonjae files he really tortured him and that doesn't help Heonjae get justice. Also, I don't know what spoilers you've seen, so I don't want to say much, but beating someone up and murder can be excused but what he's going to do is not ok, and there isn't an excuse for it.
I really don't want to spoil but there are certain acts you can't defend.
See! I told yall there was no grooming going on with the teacher. Don't get me wrong, the teacher is an asshole, doesn't deserve to be a teach, prick but yeah, I wasn't getting any pedo vibes from him.
There wasn't even any sort of misleading going on. The teacher is terrible though. Heonjae seems to be on the spectrum. He became obsessive over the teacher, only because the teacher had some faith in him. He even misinterpreted the training regimen as a "love confession"
Now, know that I'm not insulting ppl that are on the spectrum (I think I am tbh) but more of, how negatively it can effect you if you grow up in a toxic environment.
Heonjae deserved to beat up his bullies though, I an 100% down for ppl beating up their bullies. But from what I heard about what's going togappen to the teacher, NO ONE deserve that.