I don't have a lot to say about Fukushuu Kyoushitsu, unfortunately. I love the art, even at its weird and poorly drawn moments, and the premise is great. If you can stomach some gore and psychotic, horribly cruel teens, its a worthwhile reading. However, the quality of the writing greatly decays from mid-end and the ending is so bad, its laughable.
"Fukushitsu" has very good characters, though. I wish they could be more carefully fleshed out. It explores the sick mentality of broken teenagers who are left on their own, exposed to such cruelties, that they go borderline mad and lash out on different ways. Ayana, the protagonist, is kind of developed and her feelings are palpable.
Giving it a 4.5/5 because of how much the plot decayed thorughout the story. Could easily be one of my favorite mangas if it wasn't for that, lol.
Have a good day.