A Certain Magical Index

is a Japanese light novel series written by Kazuma Kamachi and illustrated by Kiyotaka Haimura, which has been published by ASCII Media Works under their Dengeki Bunko imprint since April 2004. Yen Press has licensed the novels in North America.

Synopsis
Academy City, a technologically advanced independent city-state located in the west of Tokyo known for its educational and research institutions, and populated with those of supernatural abilities. A young high school student named Tōma Kamijō has an unusual ability until he encounters an English nun named Index. His ability and relationship with Index prove dangerous to other sorcerers and Espers who want to discover the secrets behind him and Index, as well as the city.

A Certain Magical Index
Adaptation of the first 6 volumes of the light novel. Aried for 24 episodes between October 5, 2008 and March 19, 2009

A Certain Magical Index II
Adaptation of Volume 7 - 13 and SS of the light novel. Aired for 24 episodes between October 8, 2010 and April 1, 2011

A Certain Magical Index III
Adaptation of Volume 14 - 22 of the light novel. Aired for 26 episodes between October 5, 2018 and April 5, 2019