アケディア

Highly knowledgeable in the magic arts, he can use a large array of spells. His body is comprised of two heads, one that belongs to himself while the other belongs to his sister, Scholastica. Being apostles of Index and subordinates of Georgius of the Rainbow, he and his sister fought with the other members of the Punishment Squad against Liselotte in the past; and although they died, they were revived afterwards by Misao using a single body for both of them. Their Index names are "Benedictus of the Bookshelf" and "Scholastica of the Bookshelf". [Edited from the 11eyes wiki]