* Based on a manga by the same name, written by Kazuma Kamachi and illustrated by Motoi Fuyukawa, which in itself is a spin-off of the light novel, manga and anime series Toaru Majutsu no Index.
Academy City is the home to circa 2.3 million citizens, about 80% of whom are students working to develop psychic powers and advanced technology. Students are ranked according to levels corresponding to their psychic powers: those without any are ranked at Level 0, and those with some manner of powers progress from Level 1, the weakest, to Level 5, the strongest. Only seven students in the whole city are ranked Level 5, and these seven are ranked among themselves as well.
Electro-master Mikoto Misaka is a headstrong Level 5 esper, ranked third in the city. Her perverted and passionate roommate, Kuroko Shirai, is a Level 4 Teleporter and a member of law enforcement and public safety corps [Judgment]. Kazari Uiharu is Kuroko's shy Level 1 partner at Judgment and a specialist at hacking and information gathering. Ruiko Saten is Kazari's mischievous friend who has a habit of flipping the latter's skirt to find out what color of underwear she is currently wearing, much to her chagrin, and a Level 0.
Those four friends would normally be simply carrying on with their daily lives like always, but some sources of disturbance to their routines have surfaced. Recently, several strange urban legends have surfaced in Academy City: a mysterious woman who will simply strip in the middle of the city, seemingly oblivious to everyone around her; a boy of unknown powers who can easily negate any force and deflect any attacks, no matter the form they take; a way to artificially increase one's psychic level, quickly making many students into much stronger espers than they were before, and which might work even for those ranked Level 0...
Almost as if these legends themselves weren't strange enough on their own, something even stranger takes place: while there may be some exaggerations in how they are told, they are, one by one, all confirmed to be, in essence, true. And since people often tend to become drunk with power, the case of artificial powering-ups has some quite disturbing ramifications: increased powers in the hands of reckless people is quickly leading to more and more severe crimes...
— written by Hinoe and foo2
Note: This side story is set before and during the same time and location as the events of the Toaru Majutsu no Index light novels.