The story begins as Miyabi Aizawa, of the class committee from Meishu Gakuen High School’s class 2-4, spots an opportunity to cause some trouble by tricking their current homeroom teacher, Azusa Fuyutsuki, into lecturing a group of noisy guys at a bus station. Just as they are about to take her away and do unpleasant things to her, none other than infamous delinquent-turned-part-time-gardener Eikichi Onizuka swoops in to save her. As it turns out, he is currently doing gardening work at the very same school.
Just before class starts that morning, rich girl Anko Uehara and two of her friends ask resident bullying victim, Noboru Yoshikawa, to take a walk outside with them. He’s reluctant to follow along, but does so when confronted with a humiliating photo the girls have taken of him previously. After an additional round of bullying, Anko and her friends return to class while Noboru decides to commit suicide. After having made his way to the school roof, he is greeted by Onizuka who is working in a nearby tree top, and reconsiders.
Later, while on a break from working, Onizuka witnesses a group of expelled students attacking the school as he is talking to the old lady who runs the cafeteria. Head Teacher Hiroshi Uchiyamada, who has his eye on a position as Principal, orders Onizuka to deal with the trespassers, but when his verbal treatment of the group becomes overly abusive, Onizuka turns on the Head Teacher instead.
Having lost his job, Onizuka returns to Nagisa, the Café and Diner run by his best friend and roommate Ryuji Danma. Before long, their cop friend Toshiyuki Saejima shows up with his catch of the day: Noboru, who was found following Onizuka. After being told Noboru’s story, Onizuka decides to help him get even.
Onizuka and Noboru find Anko and her two friends at a karaoke place, where Onizuka proceeds to tie them up and take an embarrassing photo of them.
But after returning to the café, Noboru regrets taking such extreme actions, telling Onizuka and his pals about his past friendship with Anko and how he once betrayed her when she needed his help, prompting the bullying.
On his way home, Onizuka meets Anko, who thanks him for “setting her straight” and explains that her poor treatment of Noboru comes from her own feelings of loneliness and sadness that her parents are never home. She gets him to take her home with him, and once inside, attempts to seduce him. But as soon as it looks like they’re about to get intimate, a group of thugs walk into the room, having taken pictures of the situation for the purpose of extorting money. After Anko leaves, they demand Onizuka pay them 3 million yen for the pictures. Just then, Ryuji and Saejima enter, and the thugs realize too late who it is they’ve been messing with.
After getting beaten up and robbed by the trio, the thugs catch up with Anko and demand she pay them back – with her body. They take her away to an abandoned factory, unaware that Noboru has been following them. He calls Onizuka for help, but is told to man up and deal with the situation himself for once. He does, running in and interrupting the gang as they’re about to have their way with Anko, but gets beaten up badly. At this point, Onizuka rides in and saves the day.
The next morning, Anko thanks Onizuka for helping and tells him about her frustrating home life. After her family became rich, she explains, they’ve moved to a big house where they all have separate rooms, and they no longer talk to each other. Her mother and father are separated by a thick, cold wall – literally as well as figuratively.
Anko returns home with new determination to change herself and her family. Her parents, however, are unwilling to listen, and quickly fall into a cold, hostile discussion. Seeing this, Onizuka bursts into their home, find her parents’ rooms and knocks a big hole in the wall between them before leaving.
Later that day, the school cafeteria lady, a.k.a. Ryoko Sakurai, the Director of the school, finds Onizuka and informs him that Anko’s parents credit him with having recovered their daughter as well as helping them overcome their relationship struggles. She goes on to offer him a teaching position at the school.
Upon arriving on his first day at this new job, Onizuka is told he is to take charge of class 2-4, a group of notoriously troubled kids.
After introducing himself as “Great Teacher Onizuka”, he recognizes Noboru and Anko among the students but doesn’t think there’s anything troublesome about the class. After school, he is approached by Miyabi, who asks his help to find out why her classmate Miki Katsuragi isn’t showing up for class. After he leaves, she informs the other kids of her plans for getting Onizuka fired, then calls Miki and tells her the new teacher is on his way.