Twenty-two-year-old Eikichi Onizuka—ex-biker gang leader, conqueror of Shonan, and virgin—has a dream: to become the greatest high school teacher in all of Japan. This isn't because of a passion for teaching, but because he wants a loving teenage wife when he's old and gray. Still, for a perverted, greedy, and lazy delinquent, there is more to Onizuka than meets the eye. So when he lands a job as the homeroom teacher of the Class 3-4 at the prestigious Holy Forest Academy—despite suplexing the Vice Principal—all of his talents are put to the test, as this class is particularly infamous. Due to their utter contempt for all teachers, the class' students use psychological warfare to mentally break any new homeroom teacher they get, forcing them to quit and leave school. However, Onizuka isn't your average teacher, and he's ready for any challenge in his way. Bullying, suicide, and sexual harassment are just a few of the issues his students face daily. By tackling the roots of their problems, Onizuka supports them with his unpredictable and unconventional methods—even if it means jumping off a building to save a suicidal child. Thanks to his eccentric charm and fun-loving nature, Class 3-4 slowly learns just how enjoyable school can be when you're the pupils of the Great Teacher Onizuka.

Ishiyama High is a school populated entirely by delinquents, where nonstop violence and lawlessness are the norm. However, there is one universally acknowledged rule—don't cross first year student Tatsumi Oga, Ishiyama's most vicious fighter. One day, Oga is by a riverbed when he encounters a man floating down the river. After being retrieved by Oga, the man splits down the middle to reveal a baby, which crawls onto Oga's back and immediately forms an attachment to him. Though he doesn't know it yet, this baby is named Kaiser de Emperana Beelzebub IV, or Baby Beel for short—the son of the Demon Lord! As if finding the future Lord of the Underworld isn't enough, Oga is also confronted by Hildegard, Beel's demon maid. Together they attempt to raise Baby Beel—although surrounded by juvenile delinquents and demonic powers, the two of them may be in for more of a challenge than they can imagine.

After succeeding in their winter conflict against Taiju Shiba and his Black Dragons, the Tokyo Manji Gang absorbs their group's remaining members. Due to his heroic courage and indomitable spirit, Takemichi Hanagaki should have accomplished his goal of defeating the tragic fate awaiting his girlfriend, Hinata Tachibana. In reality, Takemichi's troubles are far from over. Although Takemichi's actions have exposed Tetta Kisaki's treachery, the conniving schemer has found power elsewhere: Tenjiku, a dangerous gang led by the enigmatic Izana Kurokawa. Izana sets his sights on Manjirou Mikey Sano, pursuing a vicious interest in the Tokyo Manji Gang's aloof leader. In the future, Takemichi discovers that the machinations of Izana and Kisaki led to Mikey's moral ruin—a downfall that directly results in Hinata's death. Unfortunately, a terrible loss robs Takemichi of his time-leaping ability, stranding him in the past with one final chance to rescue everyone he loves.

Ever since Haruka Sakura joined Furin High School, where its students call themselves Bofurin and protect the town of Makochi, he has gained new friends despite his initial skepticism. Now starting to learn how to fight alongside his classmates and slowly growing out of his solitary past, Sakura has become the grade captain of the first-years. Sakura's skills are put to the test when he and his classmates are faced with KEEL—a delinquent group known for its ruthless violence and coercion. While KEEL seems to be another rowdy group at first glance, their sudden appearance and strength in numbers might just be hiding a greater evil behind it. With all the odds against the Bofurin members, Sakura must accept that recognizing his shortcomings and receiving help from his upperclassmen will be necessary to preserve the peace in Makochi.