Index Librorum Prohibitorum

Index, also known by her full name Index Librorum Prohibitorum, is one of the main heroines and the titular character of the series. She is a young nun from Necessarius, a branch of the Church of England.

Index is small in stature and has a petite build. About 14 or 15 years old, she has thigh-length, silvery-blue hair with very white skin and large green eyes. She also wears a white robe with golden embroidery sewed onto every edge of it, the Walking Church.