Former juvenile delinquent Onizuka finds himself thrust into to role of high school teacher, facing students who behave just as he used to and an administration that doesn't trust him. Using the brash an unorthodox methods he picked up in his youth, Onizuka manages to reach through to his kids and help them with their problems. (Source: Tokyopop) 
Notes: 
- Won the 22nd Kodansha Manga Award for Best Shounen Manga. 
- The chapter count includes the 7 chapters extra GTO: Great Toroko Oppai♡ (Tomoko's Big Adventures) published in volumes 11 and 12, and one extra published in volume 25.

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. Perfect, because Onizuka's methods won't be found in any teaching manual; he cares about the difference between legal and illegal activities about as much as he cares for the age difference between himself and a high school girl. 
So get ready for math that doesn't add up, language you'd be slapped for using, and biology that would make a grown man blush... unless of course, you're the Great Teacher Onizuka. 

 Note: Episode 1 has an airtime of 48 minutes.

Before Eikichi Onizuka would become the "greatest teacher in the world," he and Ryuji Danma were members of the infamous biker gang, Oni Baku. When they weren't out riding around and getting into trouble, this duo could be found in school. Doing what you ask? Picking up young women of course! 
(Source: Tokyopop)

Great Teacher Onizuka is back, and the next stage for his legend is … prison?! The trouble magnet of a teacher reveals that this stint behind bars is thanks to a certain incident with the class he became assistant homeroom teacher of half a year earlier: Kissho Academy’s new class for high school-aged celebrities! Does he regret the exploits that landed him in the slammer? Heck, no. In fact, he’s all too happy to calmly tell his fellow prisoners how the whole thing went down—if they’re willing to listen to his story from the very beginning…
 
(Source: Kodansha USA)
 
Includes a one-shot and two extra chapters

Fujisawa’s latest hit GTO: 14 Days in Shonan revives his most beloved franchise by introducing a new challenge for his unique anti-hero, Eikichi Onizuka. After accidentally compromising his school’s reputation, Eikichi (a.k.a. the GTO) goes home to the peaceful shores of Shonan to lay low until the heat dies down. However, Shonan itself hasn’t escaped its own share of troubles, and Eikichi is inspired to help a group of troubled foster children get back on the track to happiness. Using humor and a person touch to teach today’s youth, Great Teacher Onizuka continues to impart life lessons while rarely testing kids in the classroom.
 
(Source: Kodansha USA)

Known as the gargoyle of Inogashira Park police station because of his scary face, Saejima Toshiyuki was a loser. He's pretty much a virgin for all intent and purposes, aside from the companions that he pays for. He wasn&rsquo;t always a loser though. During his high school days, he was feared as a badass, but now he is just a person people feel sorry for. He then meets Arimori Shizuka, a beautiful girl that seems comfortable in her sexuality. Toshiyuki learns that she was a high class escort that has been with over 1000 men. She was doing it out of love for her abusive boyfriend but, realizing her mistake, quits. Shizuka is now being harassed and Toshiyuki reverts back to his aggressive personality to protect the love of his life.

Being one of the few longtime friends with Onizuka (GTO), Danma Ryuji has seen all the fiascoes he has gotten into. But the motorcycle shop owner and self proclaimed fastest driver in the city is about to get into a world of trouble. A hot teenager named Ishikawa Mimon starts taking interest in Ryuji, but contrary to her appearance, she's a dangerous person that will put Ryuji into life threatening situations. Even though he has a beautiful girlfriend named Nagisa, Mimon is about to wreak havoc in Ryuji&rsquo;s peaceful life. 
(Source: MangaHelpers)

Before Eikichi Onizuka became a legend, before Onibaku, before he became GTO, he was just a normal junior high school delinquent. Getting into fights with his seniors, trying to pick up girls and just hanging out with his friends. Bad Company is a compilation of many short stories, linked together with the characters of Eikichi, Ryuji and their school buds. Such stories involve the origins of Eikichi`s bike, which we see frequently in GTO, the first meeting with the Midnight Angel and many other.

Crossover between Ino-Head Gargoyle and Kamen Teacher.

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