Orsola Aquinas

 Orsola Aquinas (オルソラ＝アクィナス) is a former Roman Catholic nun introduced in Volume 7.

She used to be a decoder for grimoires and other magical texts, and was able to decode "The Book of the Law", a powerful Roman Catholic Church grimoire. Because of this, she was captured along with The Book the Law by the Amakusa Catholics. The Roman Catholic church sent the Anieze Forces to save her, while Necessarius sent Stiyl, who dragged Index and Touma with him.

It was then revealed the the Amakusa Catholics were actually trying to save Orsola, and that the Anieze Forces were sent to dispose of her because the Roman Catholic Church labelled her as dangerous because she could decode The Book of the Law. She was saved by Touma and company, and became a decoder for Church of England. She works alongside Sherry Cromwell, and the two of them get along somewhat in Volume 9.

She usually wears a black nun's robe from her days back in the Roman Catholic Church, but as of Volume 16, she changes to a plain white nun's robe of the English Anglican Church. She has a unique way of talking; according to Touma, her way of thinking resembles that of a grandmother.