Kamijou Touma is a student living in Academy City, a highly advanced place in terms of technology. Despite being gauged as a level zero esper (no powers), he possesses on his right hand the Imagine Breaker, an ability that negates any power whatsoever. Touma finds a young girl named Index who is trying to run away from Necessarius, a powerful magic organization that she is member of. Blessed with the skill of memorizing any sort of information, she holds 103,000 forbidden magical books within her head. As science and magic cross paths, Touma must face several dangers amid espers and magicians who appear at the exciting scientific town.
Index is still a fugitive and many powerful magical organizations and individuals want to take her to use the books in her memory, eliminating her in the process. War between those organizations is also starting to emerge. Index can only rely on her friend Tōma, who has always protected her, along with Misaka and other friends from the Academy.
Academy City is a highly developed place in terms of technology. It is said to be 20 to 30 years ahead of the rest of the world. Eighty percent of its 2.3 million residents are students. The focus of studies here is directed towards esper powers. Misaka Mikoto, one of the top level espers in town, shares a room with Kuroko Shirai, another high level esper who is a member of Judgement, a law enforcing agency composed of students. Both attend to Tokiwadai, a private school reserved for the high-leveled and the rich. Kuroko's partner at Judgement, Kazari Uiharu, is a low level esper who studies at Sakugawa middle school. Her best friend and classmate there is Ruiko Saten, a level zero (no esper powers). Together, the four encounter several adventures in the exciting scientific town.
Mikoto Misaka, one of the strongest Level 5 espers in Academy City, gave her DNA map to a certain doctor when she was young, believing that it may be used for greater good. Unfortunately for her, it ended up being used to create countless clones of herself; forming the Misaka network, in order to create the strongest esper by sacrificing these clones whom she considers as her own sisters.
AD. 2023, Tokyo. Because of the change of the society such as internationalization and enlargement of the trading, the dark side of the society also continues changing. The criminals are getting deep, and their organizations are increasing its size, then the peace and security is getting worse. The government takes it seriously, and decides to introduce an innovative system. In order to cope with the special criminals, an extralegal police is founded. It is a special criminal team, Warriors, which consists of a few elite members.
Special abilities occur among a small percentage of boys and girls in puberty. Yū Otosaka uses his power without others knowing, and lives a fairly normal, average school life. Before him suddenly appears a girl, Nao Tomori. Due to his meeting with her, the fate of special power-users will be exposed.
In Tokyo, an impenetrable field known as "Hell's Gate" appeared ten years ago. At the same time, psychics who wield paranormal powers at the cost of their conscience also emerged. Hei is one of the most powerful of these psychic agents, and along with his blind associate, Yin, works for one of the many rival agencies vying to unlock the mysteries of Hell's Gate.
In the future Japan has become a fractured country, and small towns now exist. The rulers of this world have the cursed power of Telekinesis. When an incident occurs, 5 children come to realize the world is not as it seems, and learn the bloody history behind this world. These 5 children unite and help the world as it falls into a downward spiral of chaos.
"Mob" is a boy who will explode if his emotional capacity reaches 100%. This boy with psychic powers earned his nickname "Mob" because he does not stand out among other people. He keeps his psychic powers bottled up so he can live normally, but if his emotional level reaches 100, something will overwhelm his entire body.
Rinka Urushiba is a normal high school girl, until she encounters a penguin and shoals of glowing fish swimming through the sky. She looses consciousness only to awaken with the power to move through inanimate objects. At first she thought it was a hallucination if it were not for Kyotaro Azuma who witnessed the event and who, incidentally, has the ability to teleport. They decide to use their powers to combat people who might use their powers for evil.