A Certain Scientific Railgun (とある科学の超電磁砲, Toaru Kagaku no Rērugan?) is an anime series based on the manga of the same name, which in itself is a spin-off of Kazuma Kamachi's light novel, manga and anime series A Certain Magical Index. The manga is serialized in Dengeki Daioh and is written by Kazuma Kamachi and illustrated by Motoi Fukuyama. Set in Academy City before and during the events of A Certain Magical Index, the plot focuses on Mikoto Misaka, an electromaster who is the third strongest esper in Academy City, along with her friends; Kuroko Shirai, a Teleporter and Mikoto's roommate, Kazari Uiharu, Kuroko's partner in Judgment, the city's public safety committee and Ruiko Saten, Kazari's friend and classmate.

The anime is produced by J.C.Staff and directed by Tatsuyuki Nagai, series composition by Seishi Minakami, music by Maiko Iuchi, character design by Yuichi Tanaka and art and sound direction by Tomonori Kuroda and Jin Aketagawa respectively. The anime began airing on Tokyo MX from October 2, 2009 to March 19, 2010 and were later aired a day later on Chiba TV, MBS, TV Saitama and TV Kanagawa. The first 12 episodes follow the manga closely, with some changes and a few anime-original episodes and characters, while the later half of the series being a new original plot written by Kazuma Kamachi. Eight DVD compilations, each containing three episodes and a mini A Certain Magical Index novel written by Kazuma Kamachi and art by Haimura Kiyotaka which features Kaori Kanzaki as the protagonist, were released since February 7, 2010. A five minute bonus episode was included with the Official Visual Book of the show released on July 24, 2010. An OVA episode was then released on October 29, 2010. Funimation licensed the series in North America and released the series on DVD in April 2013.[1] A second anime season, titled Toaru Kagaku no Railgun S, began airing on April 12, 2013 and is being simulcast by Funimation.[2][3]

The first season features five pieces of theme music, two opening themes and three ending themes. For the first 14 episodes, the opening theme was "Only my Railgun" by fripSide, while the ending theme was "Dear My Friend -Mada Minu Mirai e-" (Dear My Friend －まだ見ぬ未来へ－, Dear My Friend -Towards an Unseen Future-?) by Elisa. A special ending theme, "Smile: You & Me" by Elisa was aired on episode 12. From episodes 15 onwards, the opening theme was "LEVEL 5 -Judgelight-" by fripSide and the ending theme was "Real Force" by Elisa. In the OVA, the opening theme was "Future gazer" by fripSide while the ending theme was "Special "ONE"" by Elisa. For the second season, the opening theme is "Sisters' Noise" by fripSide whilst the ending theme is "Grow Slowly" by Yuka Iguchi.