Despite 80% of its 2.3 million population being students, Academy City is far more advanced than any other nation worldwide. Its residents awaken something akin to a supernatural ability inside them, which is then ranked from Level 0 to 5. Along the lines lies Touma Kamijou, a powerless Level 0 esper. While his abilities are recognized as useless, he possesses a mysterious phenomenon known as "Imagine Breaker," which allows his right hand to nullify any supernatural powers upon coming in contact with them. Despite that, he claims to have rotten luck due to the misfortunes that frequently happen to him. One day, a girl calling herself Index Librorum Prohibitorum mysteriously lands on Touma's balcony and explains to him that she is being hunted down by magicians. This leads the powerless boy to discover a whole new world—one where magic exists. With Touma facing the problems that arise from both the scientific and magical sides of the world, how will he resolve them? [Written by MAL Rewrite]

As a series, Toaru Majutsu no Index has appeared numerous times in the Kono Light Novel ga Sugoi! rankings under the best light novel category; 1st in 2011, 2nd in 2012/13, 3rd in 2014, 4th in , 7th in , 3rd in , and 9th in . The series was published in English as A Certain Magical Index by Yen Press under the Yen On imprint from November 18, 2014 to March 24, 2020.