My fav manga of all time has to be Great Teacher Onizuka. If you dont know what this manga is, I suggest you find a new hobby.
GTO is about a guy who decides to be a teacher so he can fuck japanese school girl.
But as the series progress he discover two important things: He has a conscience and a sense of morality. This means taking advantage of impressionable schoolgirls is out, but their attractive mothers are a different matter.
And soon he starts helping those kids with his own brand of moral justice.
The sequel GTO shonan days