Ah okay, so it was firecrackers, not chemicals that messed up her face. Still no wonder the others were such fucking bullies. Their parents probably made them that way.
Since Kazuya had a good relationship with Naoko, I wouldn't be surprised if he survives. Yeah, he didn't stop the bullying, but more than likely he was afraid if he did they would target him which most likely would have happened. Though, how eccentric was she for the entire school to hate her besides Kazuya? She was a cute girl.