Dye Hard: Onizuka bleached hair testify of what he used to be and are usually considered improper for a teacher. Also Kunio,to emphasize his rebellious self, a lot like Onizuka himself.
Dawson Casting: They're supposed to be middle school students, but they look 16.
They're third year middle school students/ninth graders (Class 3-4 means the fourth class of third year students), meaning they're between 14 and 15. In the Tokyopop translation, however, several characters including Tomoko are inexplicably referred to as 16.