From Tokyopop:
Before Ekichi 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!

Description
Tohru Fujisawa attends AKB48's 19th Member Selection Rock-Paper-Scissors Tournament held at the Nippon Budokan on the 21st September, 2010 and draws a one-shot from his POV as part of the AKB Observation Section. Titled Repoman Soul!, it showcases the soul of the fans at the AKB48 event!

Source: mangaupdates

Murakami Shou has been putting years of blood and sweat into G&G Gold, a large banking company. He came up from nothing, worked insanely hard and now lives very comfortably, even having Rei, the hottest girl in the company, as his girlfriend.

But all that starts to slip away when Kirishima Joe comes into the company. With his handsome looks, impeccable style, calm demeanor and well endowed manhood, Joe has been upstaging Shou in every aspect of his life. And when Joe takes Rei away from him, Shou snaps and takes any measure to destroy Joe's life. But Joe has a secret that makes him hard to break.

(Source: MU)

Meet Eikichi Onizuka, a 22-year-old ex-biker. He's crude, foul-mouthed, and has a split-second temper. His unlikely goal: to be the Greatest High School Teacher in the World! Of course, the only reason he wants to be a teacher is so he can try to score with the hot students...

Before he can become a full instructor, he's got to work as a student teacher to earn his credentials.

Onizuka may think he's the toughest guy on campus, but when he meets his class full of bullies, blackmailers, and scheming sadists, he'll have to prove it.

Won the 22nd Kodansha Manga Award for Best Shounen Manga.

Hikaru Onuki is a 22 year old girl whose hobby is to cook homemade cuisine in order to find a boyfriend. But for some reason, no matter how hard she tries, she is unable to find one.

Rose Hip Rose is a manga about a teenage girl who fights crime. While the setup doesn't sound so great, it gets better as the manga progresses. The series' major strong point is the art. Along the way, she ends up having a showdown with a major criminal named The Goat. However, it seems that The Goat doesn't seem to like being caught. Be wary, though, the series is very violent.

The art and story are by Fujisawa Tohru, author of GTO and Bad Company. The art is quite nice, but somewhat different from GTO's. If you like violence, gore, Fujisawa, or cacti, Rose Hip Rose is the manga for you. Oh yeah, did I mention it was violent?

Kazuki Suwa is a first-year high school student. Every day after school, he goes home and plays video games. His Mother does not approve and asks him to choose a club in high school. But Kazuki does not really have any skills or talents. But then he meets Nanako Kunii, the club president and only member of Research Dutchoven Club, a club where Nanako focuses its research on the use of Dutchoven.

Teenager Hideki Yuu finally musters up the courage to confess to his crush, Miki, only to have her reject him. Three days later, she becomes an idol...

Fujisawa Toru’s debut manga.

GTO: Paradise Lost is a sequel to GTO and Onizuka is now 24 years old as well.
Onizuka is a prisoner. For reasons that he only knows, he tells the story himself of what happened between him and Class G (which is basically an idol class), expect many troubles, adventures and of course many hilarious moments

Ikewaki Gajirou, nicknamed Gacchan, is the most valorous of the Big 5 in his school. He's a pretty good person. However, he has one flaw that people fear him for...

After being reformed by the GTO, Eikichi Onizuka, the Twins of Terror, Riko and Miko Sakaki, leave their past behind and become members of the Disciplinary Committee at their school, Chigasaki Kahoku Private Academy, helping fellow students in need through an SOS messaging system. When an illegal prostitution auction ring is uncovered at their school, the twins set out to restore peace to their school and punish those responsible, GTO-style!

Spin-off of GTO - Shonan 14 Days.

Kyokuran is a public high school with 80% delinquents.
Araki Gota and Kamen Teacher are new teachers that have been hired to solve the problems in their own specific ways.

Story about a boy raised like a girl by his parents. This in order to let him succeed in the family traditional theatre where the male actor must act like a woman. (Source: M-U)

This is a spin-off story of the manga GTO(Great Teacher Onizuka). This takes place directly after the Teshigawara arc[after he was shot by him]

After Eikichi Onizuka was shot by the former teacher Teshigara, he was sent to the hospital. Shortly afterwards he escaped, then disapeared for 14 days after an incident involving a t.v. appearance. Strangely enough, when he returned, a wanted poster appeared with a man that resembled very much like Onizuka. What exactly did he do during those 14 days?

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.

The evil Solomon's Child are turning people into Red Dust and it is up to our heroes Shik and Ryoji Kamishiro and the rest of the gang to stop them. Will our heroes stop the Solomon's Child? Or is there something bigger waiting for them on the other side? Read and find out.
(Source: Mangaupdates)