Raildex is the nickname the English-speaking fandom uses for the Toaru Majutsu no Index franchise. It is a portmanteau of Railgun and Index, referring to the animated adaptations. The Japanese equivalent of this is Toaru (とある Toaru?, lit. "A Certain"), referring to the first three hiragana characters that is now part of the idiosyncratic naming scheme the franchise uses for its series and other properties.