Perfect! Except maybe yandere part.
And she didn't lost her eye. It's just a patch to hide her black eye.
I always wonder where the hell are the parents/teachers/police in these kinds of story
Depends. Parents maybe too busy at jobs, teachers don't give a heck and police overload with things a lot worse so they didn't care about "minor" cases like this one.
I almost killed on of the bullies back in my school days. I'm glad I didn't. Because literally no one cares if you're bullied or not, but if you kill someone you're became a murderer and this will have a lot of bad consequences for you.
Actually teachers can and MUST stop this. When I saw someone being bullied I just make sit down all bullies to their sorry asses and tell them that if I see that again they WILL regret it. And lucky me because I have some degree of freedom and I can just literally throw out and ban from attending my classes anyone who troubles their classmates or interfere with my lessons. Sometimes their parents bring them back but I always make one condition that this never ever happen again. And they didn't promise it to me, they promise it to their parents so if anything this will be their family problems, not mine.