As a spinoff of A Certain Magical Index, A Certain Scientific Railgun follows the daily life of Mikoto Misaka in Academy City. Being a self contained environment for the study and advancement of espers, life in Academy City is rarely mundane. The excitement picks up as a string of crimes breaks out, all involving espers abusing their powers for whatever reason. Being the roommate of a Judgment member, Mikoto gets drawn into their investigations and peacekeeping activities.