Kamiyama is a regular nice and well behaved guy who gets good grades in school. Which would be fine and normal in any other school, but Kamiyama goes to Cromartie High School, the toughest school for delinquents in Japan. Furthermore everyone assumes that since Kamiyama is so normal, smart, and not insane he must be the toughest guy at the school based on the principle that a bunny that lives amongst lions must be the most bad-ass bunny in the world.
As if this was not enough, the student body includes:
a tin can style robot that does not realize he is a robot who has a little brother that doubles as a cell phone
a would-be world conquering supergenius and his nameless lackey
at least 1 alien
a terrorist that assumed the identity of one of the students after a botched airplane hijacking and kept said identity after the student returned to class (now it is student 1 and student 2 and they have to share a desk) who secretly wants to be a Mexican wrestler.
A guy with very animated hair that is actually a wig he wears to make himself seem like a delinquent
A guy who gets kidnapped every couple episodes and a rescue party is formed to save him but they keep getting lost or distracted and thus never actually save him