This dark comedy sure sparked a lot of discussion.
"systemized bullying"? Lol wtf is that. You hardly see bullying in the adult world, it's a teenage phase because emotions are high. All emotions, and by being a pathetic turd who doesn't try to stop it you become an easy target for people with high emotions. "everything she did to them they did to her" really now? Cause I don't see her missing an eye, I don't see those girls blackmailing her with photos or her with sores in her mouth. All we say was light bullying and pranks. And society didn't fail you, you failed yourself. Stop looking for hand outs and stand up you pussy!
When I think of systemized bullying, I think of the kind that you know the reason you're being picked on and you know that telling on them wouldn't help. Sometimes you know that the staff is aware and you know that if you go to them, they will actively make it worse. Even for little things they could make it worse. My sister was bullied to the point of crying, and then she was going to be suspended for crying. On the other hand, a gay boy at my school had rocks thrown at him, and no one left the school except him.
We don't even know why they regularly pick on victims to manipulate and try to push over the edge, but since the three of them called Icchan out into a closed room, I assume it wasn't just to have a talk. Since the story establishes that everyone around the main character knew and nothing they were doing is subtle, I don't know what "civilized" method would stop it. They held her down and cut her hair off when she tried to stand up to them before. You can't call the type of fearmongering, manipulation, and blackmail they were doing to her light bullying.
Besides, like Icchan said, she didn't kill them, and they learned their lesson. Happy ending for everyone :D