Great post..... I feel sorry for the guy banned from reading manga... I guess Marvel comics are right out as well
(with all their gravity defying ladies).
If you read further, you find that Rin's behavior is more complex (she's got a serious grudge and nasty tools to use on people she thinks are hurting her friends) ... but her attitude towards the new teacher Aoki gets very complicated -- you didn't say if you'd read volume 1 and 2 before reading some of 3.
The book is not necessarily for everyone but more because the characters may or may not be appealing to the reader. But I think you're another person that has *read* the material and asked what the overcharged lynching was all about. "16+"? sure, yeah, whatever.... "not allowed"? sad.. very sad.