I am legitimately confused. I have several questions, but honestly, I don't think I want any of them answered. In this review, I'll be writing my views regarding Fukushuu Kyoushitsu -- I'll avoid spoiling it, but be warned that this may, in fact, not be spoiler-free.

Story (3/10):
This is the story about a girl who suffered an awful amount of bullying from her classmates, and now she wants to take revenge on them in multiple forms which, initially, doesn't necessarily mean she will resort to killing everyone. After a few victims, the manga seems to attempt to show us the consequences of her acts and how selfish the progatonist was from the very beginning and gives us the expectation that things may not start to go as we initially expected and that her chain of revenge was, in fact, an awful idea.
In the following chapters, however, that seems to have been completely forgotten or discarded, as the entire story surpasses the limits of how edgy a scenario can be and everything is blown out of proportion, along with ridiculous plot twists which makes you wish they never actually happened and the worst possible depiction both of "Cause and Effect" and how serious the story is actually meant to be.
The third act and the ending do nothing to fix that, but instead, transform a certain horrible character into a secret good guy and reveals even more absurd plot twists that lead to an unsatisfactory, frustrating, and completely open conclusion.

Art (5/10):
I'll make this section short: It's OK, there is nothing particularly special about the artwork of this manga, it does just fine but does not stand out and fails to convey emotion.

Characters (1/10):
When I thought I had already seen a story full of horrible characters, Fukushuu Kyoushitsu managed to quite LITERALLY make a story which only contains characters that are completely awful. When I say that, I mean that most of the characters in this manga only have one trait, which is that they are despicable people and that is all that matters, adding to the selfish and unidimensional view of the protagonist, which is also an awful person.
No one is memorable, no one has any trait that makes them stand out or they only have a single trait that is taken to the extreme in an attempt to give them some sort of personality. Try remembering everyone's names, you won't be able to, you will easily forget the names of the main characters. Try describing them with more than two sentences, you won't be able to do that either, because there is really no depth to them at all, not to mention not a single one of them is likeable.

Enjoyment (3/10):
You know, in the beginning of this manga, I was enjoying it and I wanted more, because my expectations were that the story would develop into something far more interesting than just this "revenge chain" and get away from the one-sided, selfish and screwed up point of view of the protagonist. However, that didn't happen and, as mentioned above, became a ridiculous scenario with absurd plot twists and there was no enjoyment left by the end of the manga, because of how disappointing it was.

Overall (2/10):
Need I say more? I was left disappointed in so many levels because of how poorly written and how terribly rushed this manga turned out to be, how you never get to actually like or even remember any of the characters, how your expectations are ruined by the attempts of making a subversive plot, the reader is left confused about many unanswered questions and the enjoyment is nowhere to be found.
My recommendation is to simply ignore this manga and avoid the possibility of serious frustration and confusion.