Madonna: An OVA clocking in at not too far under two hours that's in desperate need of lovin'. Its current 6-something rating is a joke, and under 100 ratings - even though it was released in America - is puzzling. Also very frustrating is the fact I can't read the 20+ volume manga to see another possible GTO through to its conclusion...
Madonna is about a a woman fresh out of college looking for an easy life - starting teaching because of the amount of holidays she'll get. Naturally, she decides to teach at an all-male school for delinquents and finds herself needing to win over
a bunch of horny thugs; dealing with constant sexual jokes, mild rape attempts (contests over what colour panties she's wearing), and other fun. At first she's scared and on the verge of running away... but, after throwing her shoe into the face of one student and - in spite of being nervous - standing on a desk and revealing herself to be wearing a leotard, then telling the students they're still boys if they're excited over such things, she becomes the idol of their school.
As well as because of the obvious teaching aspect, Madonna is similar to GTO in the sense that the teachers in both have positive impacts on the lives of their students. Madonna's almost Onizuka-esque, hones/often amusingly silly and direct lead ends up being the manger of the school's new rugby club; motivating the students to pour their energy into something productive for her.
Extra: in episode two, there's a rugby coach introduced. He has the same voice actor/methods as the famous Gunbuster coach-person. His manly voice makes me want to reveal my chest hair to the world. read more 
