Tomoki Yanagi

Onizuka is a reformed biker gang leader who has his sights set on an honorable new ambition: to become the world's greatest teacher... for the purpose of meeting sexy high school girls. Okay, so he's mostly reformed. However, strict administrators and a class of ruthless delinquents stand between Onizuka and his goal and they will use any means, however illegal or low, to drive the new teacher away. (myanimelist.net)