A Certain Scientific Railgun S is the second season of the A Certain Scientific Railgun television anime series produced by J.C.Staff and directed by Tatsuyuki Nagai, based on the manga of the same name, which in itself is a spin-off of Kazuma Kamachi's A Certain Magical Index series. The anime series is set in Academy City before and during the events of A Certain Magical Index, in which 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.