Kuroko Shirai is a level 4 esper and a character introduced in A Certain Magical Index. While a minor character at first, she eventually gets a starring role in A Certain Scientific Railgun serving as the deuteragonist of the series. She is a member of Judgment serving as a part of the 177th Branch Office. Kuroko is a student at Tokiwadai Middle School and is the roommate and best friend of the level 5 esper Mikoto Misaka. She is voiced by Satomi Arai in the Japanese version of the anime and Alison Viktorin in the English version, the former of whom also voices Sayoko Shinozaki.