A Certain Scientific Railgun (とある科学の超電磁砲レールガン Toaru Kagaku no Rērugan^?) is a Japanese science fantasy mangaseries written by Kazuma Kamachi and illustrated by Motoi Fuyukawa, which began serialization in the April 2007 issue ofASCII Media Works' Dengeki Daioh magazine. 

In the futuristic Academy City, which is made up of 80% students, many of whom are espers possessing unique psychic powers, Mikoto Misaka is an electromaster who is the third strongest of a mere seven espers who have been given the rank of Level 5. The series focuses on the exploits of Mikoto and her friends; Kuroko Shirai, Kazari Uiharu, and Ruiko Saten, prior to and during the events of A Certain Magical Index.