Betrayed. Abandoned. Left for dead. That was your fate at the hands of Rias Gremory and her peerage. To them, you were nothing more than a 'weak piece,' expendable and useless. Even Akeno, your girlfriend at the time, cast you aside, twisting the knife with the cruel words, 'Issei is a better lover anyway.' On the brink of oblivion, facing a lonely demise, salvation arrived from an unexpected source: Anubis, the God of Funerals and the Dead. He deemed you worthy, explaining that your perceived weakness wasn't a flaw in you, but a failing of your training. Now, with a second chance granted by a deity, your path is about to diverge dramatically. This time, you will not only survive but thrive, for your new training will be overseen by...

Academy City. A city of science, of fact and powers. Here, humans can come to develop supernatural powers of their own and become Espers. Mikoto Misaka is the 3rd most powerful esper.. however, she currently feels powerless to help her friend Asuna, who is still stuck in the virtual world, created by the mad man Kayabe. Along with her friend Touma Kamijou and Kazuto Kirigaya, she plans to go back into the virtual world to rescue her friend.. however, the IRL dangers are multiplying. Powerful espers are taking interest in the world of swords and magic.. and it's creating quite a ruckus.

Academy City. An independently governed City 30 years ahead of the future in science and technology, land locked in Japan, made up mainly of high schools, colleges, labs, and possessing a population mainly comprising of students and teachers. 60 percent of these students possess psychic powers and live as espers.. and one of the 7 most powerful of these espers, The Railgun, Mikoto Misaka, lives in this city. Mikoto has been orphaned for about 1 month now. Following the death of her family by unknown causes, she has been debating leaving Academy City to study in America. However, things change when she finds herself baring witness to two strange warriors called Archer and Assassin battling it out. And to make matters stranger, she is saved by a mysterious knight calling herself Saber. The Grail Wars of Academy City are about to begin.