She's one nasty, unlikable, unsympathetic, sadistic little bitch.
There won't be a second series now. By all accounts it wasn't popular when first show, with most people being turned off by her antics (plus her classmates are complete idiots).
It was probably only done to boost manga sales (of which the story can apparently be extremely dry), and really is only of interest for those who have tried the manga.
I just hope when the manga does finish, she doesn't have a happy ending.
She never really pays any sort of price for what she does (and later on she tries blackmailing her classmates hoping to destroy their lives) , she somehow avoids the death penalty, only spends three years in jail and then escapes an internment camp.
I do think she also enjoys killing people - she was quite happy thinking about killing Mirichu and others.
At least Nana gets a taste of her own medicine at the end of the series - serves her right too - I've got no sympathy for her.
It's a shame that Nano doesn't end up killing her when he has the chance after they meet up. He would be quite justified then