the girl that revealed her self in the ending was "mayu saguya" she pretended to be the sister of the bullied guy when she talked to the mc , which means she's not his sister and that was just a part of their plan .
and the real culprit is her and the "sensei" and some others who's identities weren't revealed for the sake of the story , apparently these people help the bullied "victims" to get revenge on their bullies , so in the end we see that kanae started getting bullied and she met "sensei" which means she became a part of his association.
to sum it up kanae will also bomb her school.
I’m a bit lost of what’s going on. Someone please explain it to me in an easy way of what tf is going on. Who’s the real culprit, what happened to the sister and everything. Thank you I’m just dumb