T akashi Kamiyama, a mild-mannered high school student, tries to adjust to life in Cromartie High School. This school houses some of the biggest, toughest, and rudest delinquents in Tokyo; evidenced by all the teens smoking in the classroom and having his pencils eaten by one of them. The reason why he is here is not explained in the anime, but suggests that the viewer "reads the manga" to find out.
In his classroom, a group of students are having a bragging contest of who is the most bad-ass among them. One of the people goes by the name Maeda; who is immediately outcasted because, despite having an impressive history in fighting, he didn't have a cool nickname in Junior High. The group questions Kamiyama on the matter, but claims to have done nothing really wrong: being only an errand boy in Junior High. However, he does hint at one bad deed he did: but this, again, is not discussed and instead tells the viewer to read the manga.
Cutting back to Kamiyama, he is now reading a book that he thinks will help him become a delinquent. The book, "Debuting in High School", teaches lesson that include bleaching his hair (which turns it white and "makes him look like a pussy"), walking lazily, being around tough looking people, and dealing with childhood friends who are not delinquents. However, to his dismay, he learns that he needed to complete all these tasks before his first day of High School.
In the next scene, the class tries to decide (again) which one among them is the most bad-ass. They gather a group of students who have had plenty of past instances of violence: Kamiyama, confusingly, being one of them. From the group, the mohawked delinquent, Shinjirou Hayashida, admits to being the one who nominated him. According to him, since Kamiyama is the most normal looking and is enrolled in the school, he must have some sort of hidden dark side. In the end, Kamiyama is named the most bad-ass after a being the last one standing in a contest that this writer can't remember at the moment but will get back to you on.
In the final scenes introduce Kamiyama, as well as the viewer, is introduced to Cromartie's weirdest students. First, there's Freddie: a mute look-a-like of the late Queen singer Freddie Mercury. Next, the Gorilla; who is just a gorilla. Finally, and the most strangest of all, Shinichi Mechazawa: a robot with a calm human-like personality.