Koushiki Comic Anthology: Toaru Kagaku no Railgun featuring Toaru Majutsu no Index

Mikoto Misaka

御坂美琴

She is the third ranked Level 5 esper in Academy City, and has been nicknamed Railgun due to her signature move. Kamijou Touma coined the nickname Biri-Biri (ビリビリ, Biri-Biri) (a Japanese onomatopoeia imitating the sound of electricity), while in the English dub she is referred to as "Bug Zapper" (or more usually, simply "Zapper"), and whenever the two meet, he usually calls her that, even after his amnesia.

Bio from Fandom, licensed CC BY-SA

Kuroko Shirai

白井黒子

Touma Kamijou

上条当麻

He is a typical teenager with the usual angst and laid back attitude common for his age - this is apparent in the way he handles his guardianship of Index. In spite of being her guardian, albeit unofficially, he usually leaves Index to her own devices - often unprotected and often leaves her without an explanation which causes the latter to look for him and end up being in harm's way.

Bio from Fandom, licensed CC BY-SA

Index Librorum Prohibitorum

禁書目録

Her name is based on the book with the same name, The List of Forbidden Books or "Index Librorum Prohibitorum" (禁書目録, Kinsho Mokuroku) in Japanese. It is a list of publications prohibited by the Roman Catholic Church.

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MISAKA 10032

御坂妹, ミサカ10032号