The story of Shonan Junai Gumi deals with the Oni-Baku (Demon Explosion) duo, consisting of Eikichi Onizuka and Ryuji Danma, and their quest to lose their virginity and reach maturity. They are widely feared b?s?zoku, and are known for their tenacity and viciousness in a fight. However, this lifestyle does not exactly endear them to the opposite gender, so they decide to change their ways. However, this is easier said than done. As the story unfolds, we meet the Oni-Baku's wide range of friends and foes, and the crazy situations they all get into. The story is initially a gag manga, but more serious issues present themselves as it continues, eventually striking a balance similar to that of GTO (which this manga predates).
[color=blue]Eikichi Onizuka[/color] (????)
A former member of the Bousou Tenshi ???? (Berserk Angels) biker gang, otherwise known as the Midnight Angels, Eikichi looked on the leader Kyousuke Masaki as an elder brother. He met Ryuji Danma at Junior High (see Bad Company), where there was animosity between them, but it settled down into the strong friendship they now share. Deadly in a fight but not so skilled when it comes to dealing with women, Eikichi is a nice guy at heart (as seen in GTO) and despite his rowdy behaviour, he always manages to help people out. He lives with his mother in an apartment. Eikichi rides a Kawasaki Zephyr 1100, but is also the owner of Masaki's ZII.
[color=blue]Ryuji Danma[/color] (????)
The other member of the Oni-baku(Devil-bomb) duo, Ryuji is taller and maybe slightly more restrained than his partner, although get in his bad books and you're in for big trouble. He has more luck with women, having had a relationship with his teacher Ayumi, and later Nagisa (seen in GTO). Ryuji's family are nice, normal people, who appear quite wealthy, who totally disapprove of his 'bad behaviour', however his elder sister Yoko allows him to stay at her home when he needs to. His younger brother is called Yoshitaka. Ryuji rides a Honda CBX-400F, as seen in Bad Company.
[color=blue]Toshiyuki Saejima[/color] (????)
Along with his partner Kamata, he is feared as Kamakura no Kyouken (The Mad Dogs of Kamakura). This duo were renowned for their brutality, including shoving pencils through people's noses. (Which proves to be very ironic). However after being beaten by the Oni-Baku, the pair decided to join their gang. Saejima has a malevolent face, so much so that girls are afraid of him and assume he is a Yakuza. He, like Ryuji, comes from a fairly well-to-do family, who are terrified of him- his sisters speak to him through a lock on their bedroom door, and his parents jump at his slightest movement. Saejima rides a Kawasaki.
[color=blue]Katsuyuki Tsumoto[/color] (????)
Katsuyuki is the leader of the K.T. Butai (Katsuyuki Tsumoto Fighting Group), a kind of ‘sub-unit’ of the Oni-Baku gang, consisting of Yasuo, Atsushi, Saegusa, Kitamura and numerous other students. He has a hair-trigger temper, and as such can cause a lot of trouble without thinking about it. He has a rivalry with Tamura, and a long-standing grudge against Kenkichi Hino. He once fought Eikichi, but was beaten and decided to adopt him as a role model. He is loyal to the Oni-Baku and will fight anyone who badmouths them, but his main allegiance is to Eikichi.
[color=blue]Shinomi Fujisaki[/color] (?????)
Formerly a fat and rather unattractive girl who was defended by Eikichi in the past, Shinomi reappears as a beautiful young woman who is involved with Takezawa Akira of the Idaten gang. After Takezawa is hospitalised after fighting Eikichi and he breaks up with her, she dyes her hair blonde and befriends the Oni-Baku-gumi. She has an attraction to Eikichi throughout the series, but since he sees her more like a sister he is reluctant to embark on a relationship with her. She becomes a friend of Nagisa’s, and is often seen hanging around with her. Shinomi is feisty and packs a good punch, and personality-wise is the female Eikichi, so they are pretty well suited. Shinomi appears in GTO as Tomoko's makeup artist, and at the end of the series seems to catch on to the identity of Tomoko and Mayu's teacher.
[color=blue]Nagisa Nagase[/color] (???)
Nagisa first appears working in the Marine House seafood restaurant as a waitress, catching Ryuji's attention with her t-back bikini. However, although she seems sweet and innocent, she actually suffers from Dissociative Identity Disorder, and has an evil side who calls herself Yasha. She is a member of the Midnight Angels gang under Junya Akutsu, and is his girlfriend. Her mental disorder arose after he raped her in the past. Ryuji saves her life, and she eventually overcomes her problems and becomes his girlfriend. They are still together in GTO.