Unlike many schools, attending Hyakkaou Private Academy prepares students for their time in the real world. Since many of the students are the children of the richest people in the world, the academy has its quirks that separate it from all the others. By day, it is a normal school, educating its pupils in history, languages, and the like. But at night, it turns into a gambling den, educating them in the art of dealing with money and manipulating people. Money is power; those who come out on top in the games stand at the top of the school. Yumeko Jabami, a seemingly naive and beautiful transfer student, is ready to try her hand at Hyakkaou's special curriculum. Unlike the rest, she doesn't play to win, but for the thrill of the gamble, and her borderline insane way of gambling might just bring too many new cards to the table. [Written by MAL Rewrite]

In the backwater town of Bellforest lives a 14-year-old boy named Renton Thurston. He desires to leave his home behind and join the mercenary group known as Gekkostate, hoping to find some adventure to brighten up his mundane life. However, stuck between his grandfather's insistence to become a mechanic like him and the pressure of his deceased father's legacy, the only excitement Renton finds is in his pastime of riding the Trapar wave particles that are dispersed throughout the air, an activity akin to surfing. Everything changes when an unknown object crashes through Renton's garage, discovered to be a Light Finding Operation—a robot capable of riding the Trapar waves—specifically known as the Nirvash typeZERO. Its pilot is a young girl named Eureka, a member of the Gekkostate, who requests a tune-up for the Nirvash. Their meeting sparks the beginning of Renton's involvement with the Gekkostate as he takes off alongside Eureka as the co-pilot of the Nirvash. [Written by MAL Rewrite]

Mikoto Misaka and her friends are back, investigating rumors across Academy City. Soon, Mikoto discovers something terrifying: horrific experiments are taking place throughout the city, involving the murder of thousands of espers. Moreover, these espers are far from just ordinary people: they are clones of Mikoto herself. Feeling responsible for their treatment, she sets off to put an end to the experiments; however, the forces opposing her are much more dangerous than she anticipated, and Mikoto finds herself up against some of the most powerful espers imaginable. Toaru Kagaku no Railgun S continues the story of the Railgun as she desperately fights to put an end to the inhuman experiments that she believes she helped cause, her life dragged deep into despair in the process. There's never a dull moment in Academy City, but no one ever said all of them would be pleasant. [Written by MAL Rewrite]

The student-filled Academy City is at the forefront of scientific advancement and home to the esper development program. The seven "Level 5" espers are the most powerful in Academy City, and ranked third among them is middle schooler Mikoto Misaka, an electricity manipulator known as "The Railgun." When strange incidents begin occurring throughout the city, she finds each crime to be connected to the elusive "Level Upper," a legendary device that allegedly increases the esper level of its user. As the situation escalates, it becomes apparent that there is more to the Level Upper than meets the eye, and that Academy City may be a far more twisted place than the glamorous utopia it appears to be. Toaru Kagaku no Railgun focuses on Mikoto and her friends—and the dangerous situations they find themselves in—as they get caught up in the matter of the Level Upper. As Mikoto says, "There's never a dull moment in this city."