Yes, what she did was terrible and inexcusable, but beating the living shit out of her won't get Shouji out of this situation!
The best way to get Shouji out of it is to get the girl to confess that her claim was false, but in order to do that, violence won't cut it. You need to make her understand the gravity of her actions, and starting off by pointing fingers or acting aggressively will only make her more defensive, and given her status of victim at this point, it only gives everyone else more reason to believe in her side of the story.
Seriously, do none of you know how to human properly?