Hi guys,
I'm looking for this manga about a girl who is like a typical school girl in school who gets caught up in some wierd experiment or survival. She's doesn't know what happening and nor do the students.
There's a scene where the classroom blows up I think and her entire classroom were being shot at by someone with sniper rifle and some students were running and getting shot. In the conflict the girl mets a boy with black hair or dark hair who helps her but he is kinda a jerk who only cares about himself.
She, him and some of he survivors make it through, and friendships are formed.
Until a scene where the boy betrays her, he works for the people who are doing the experiment or whatever it is and smiles.
He's betrayal hit hits her hard.
Suddenly something in here is "awakened" and she just goes ballistic, surprising everyone even the boy who betrayed her, she starts destroy all the "soliders" even a helicopter, with this super strength or something and some other people try to capture her??
That's all I remember, I really what to figure it what manga that was. It wasnt old, the girl had personality of trying to save people and help and work together, besides her being scared and not knowing what was going on.

Please help anyone?!?!
I know it's like an action manga, survival manga. It's gory I think. And the name of it was long I think.

Jinrou Game or one of its sequels, maybe?