Index Librorum Prohibitorum

Index Librorum Prohibitorum, generally known simply as Index, is the titular deuteragonist and lead heroine of the light novel and anime series A Certain Magical Index, also making a few cameo appearances in A Certain Scientific Railgun. She is a member of Necessarius, the 0th Parish of the English Puritan Church and has an eidetic memory. She holds within herself 103,000 magical texts known as grimoires.