Eikichi Onizuka is the protagonist of the GTO series. He was formerly known as a member of Oni-Baku; Shonan's strongest fighting duo. He is a teacher at Holy Forest Academy, where he is the homeroom teacher of the troublesome class 3-4. Although he teaches social studies, he is well known for teaching lessons about life, which earned respect and loyalty of his rebelious students, one by one.
Due to his great charisma and great lessons about life, Onizuka earned respect and love of several women towards the series.
Azusa is also a teacher and Onizuka's colleague at the same school. Unlike Onizuka, She graduated from a well known university. However, Azusa feels insecure about her job, escpecially in the begining of the series, when female students grew envious of her due to attracting several boys with her good looks. Eventually, thanks to Onizuka's advice, she managed to win them fairly around. Onizuka greatly cares about her, and always consoles her and reassures her that she is a great teacher, and he is grateful for all the things she did for him, and even mentions that she taught him something important he wasn't even aware of. Azusa in return, cares a lot about him, as she helped him several times from delicate situations, which would get him fired. Azusa is truly grateful for all things Onizuka has done for her, and eventually started to gradually fall in love with him, because he was the one who taught her the joy of being a teacher. Azusa realised her feelings for Onizuka, when the latter developped a cerebral aneurysm , due to the several blows to the head he received througout the series, and one fatal blow might kill him. When Onizuka reveived the said blow, he went into a coma, and underwent a surgery with him being in a life or death situation. Azusa broke down crying, heartbroken at Onizuka's fate, but tried to put up a courageous facade in front of his students, encouraging them to believe in him. Eventually, Onizuka miraculously survives his ordeal, but became unable to teach for a while. In the end of the manga, she celebrated Onizuka's recovery at school along with his students, reflecting on how Onizuka showed her how great it is to be a teacher.
She is the second person to fall in love with Onizuka. Urumi is a genius with an IQ above 200, and also well known for her class terrorism, due to an incident when a teacher betrayed her in the past. Originally, Uurmi was antagonistic towards Onizuka, framing him for raping her, and appearing at school the other day as his student, placing a King Cobra toy in his crotch, much to his embarrrassement. Wanting to know the reason behind her behavior, Onizuka tailed her and got himself spotted by her, they went afterwards to a ramen restaurant, when Urumi told Onizuka that generally teachers won't hesitate to abandon their students in a delicate situation. Onizuka replied that he isn't the type who would discard his students. In order to test Onizuka's true personality; Urumi began causing mischiefs such as throwing a bottle at a Yakuza boss and threatning to suicide from a high building. Eventually, Onizuka accidentally pushed her off the building, and Urumi was surprised to see Onizuka jumping after her in order to save her. The two landed on boxes, but Urumi pretended to be dead, to test Onizuka's character. While being spotted by the police, Onizuka run away carrying her, believing her to be dead, decided to bury her deep in the forest, however, he scolds himself for doing so while he doesn't know that she is certainly dead. Onizuka tried to perform a CPR, only for Uurmi to wake up, scaring him and telling him to stop killing her. Afterwards, Urumi forced Onizuka to be her genie of the lamp if he wanted her to keep quiet at his burying her alive attempt. The day after, Urumi meets her former teacher who betrayed her in the past, and welcomed her by throwing a chemical explosive at her face. Onizuka slapped her for doing so, which caused Urumi to storm off and launching several explosives at school, damaging it. Onizuka and his students had a talks with her teacher, when the teacher reveals the reasons behind her recent behavior as well as her secret, which turned out that Urumi is a test tube baby born with her mother's egg and the sperm of a genius scientist. Eventually, Onizuka gave a near death experience to Urumi which made her cry in tears. Afterwards, Onizuka tells Urumi that he understood the reason behind her recent behavior, but introduced her to a member of gangs who had much worse problems than her, but managed to overcome them. Urumi realises soon how crazy she had been acting and finally started to change for better.
Realising that Onizuka will do anything for his students, Urumi falls in love with him and became one of his greatest allies. She eventually became protective towards him, and will go berserk on anyone trying to harm him, such as when she hired a group of rapists to punish Miyabi and her gang for framing Onizuka to get him fired. She finds Onizuka as the real reason she lives for. When Onizuka went into a comatose state due to his crebral aneurysm, Urumi broke down crying, and was willing to kill herself in case Onizuka doesn't survive. True to her words,she cut her wrist with a cutter knife when Onizuka's condition worsened. Fortunately, Onizuka survives miraculously, and Urumi later attends a festival to celebrate his recovery.