One thing for sure, the true sinner is that pedophile teacher. He's the reason why this tragedy happened.
But, truth to be told, I really hate both the lead characters personality. Male MC is an idiot who only think of himself and his crush. He doesn't think of his familiy and friends. There are so many ways to tell the truth, like he could tell the truth with some white lies in it. But he chose to be a hero. What he did is to complicate things. I know that if I'm his position, I also take into action to beat that pedo teacher but not to this extent to destroy my family/friend. He could just record it with his phone.
I feel sorry for the Female MC, to be raped multiple times is really traumatic. The only thing I don't like about her is she did not tell anyone about being raped by her teacher, even her mom did not know of what's happening with her own child. Furthermore, I really understand why her brain suddenly cannot remember of what really happened on that day, it's defense mechanism.
Male MC best friend and his mom is the real MVP.