Agnese Sanctis (アニェーゼ＝サンクティス Anyēze Sankutisu) is a Roman Catholic Church nun who leads a paramilitary force called Agnese Forces. A girl with a troubled past, her devotion to her religion makes her out to be a totally ruthless leader against enemies. She is first introduced in Toaru Majutsu no Index as an antagonistic character, but later reforms and joins Necessarius, and is a representative of Roman Catholicism in England.

Agnese looks a year or two younger than Index, but still around the same height. She appears extremely thin, as her slim waist was even slimmer than Index's, who was rather thin herself.
Her reddish hair is tied into with multiple pencil-thin braids, which from a distance bear an uncanny resemblance to dreadlocks. She wears the standard Roman Catholic Church robes. The sleeves being so long that it nearly covers her fingers, the hem of her robes however is short enough for her thighs to be exposed, this is due to the fact that she unzipped and removed the rest of lower of half of her robes, zippers being part of the ensemble.

She wears platformed shoes called chopine which have 30 cm thick soles. She usually wears them over her usual form of footwear and during combat they can be removed to enable better movement. Despite walking on it, she insists on wearing them as she says that it is her sense of beauty.

Agnese also wears a Roman Catholic cross on her neck.

Agnese, when not on duty, acts like other girls her age. She is clumsy, particularly due to her choice of footwear, which she refers to as her own style; she gets embarrassed when something lewd happens to her, such as when Touma fell between her thighs; and is afraid of slugs. Like many people from the magic side, she is intimidated and somewhat impaired by technology, such as when the washing machine she uses goes haywire after stuffing an entire futon into it.
Agnese also does not like the idea on having to converse with someone who is foreigner using the foreigner's native language, opting that she would rather have them converse in other tongues. Indeed, Touma describes her way of speaking Japanese as strange, and is referenced as a mix of Japanese polite honorifics and rude words, and is thought by Stiyl Magnus as someone who has learned Japanese from talking mostly to detectives or police officers.

She also apparently sleeps in her underwear, and walks and talks in her sleep, though this has only been seen once.

However, as the leader of the Agnese Forces,
she is extremely devoted to the cause of her Church, using deceit on others such as when she tricked Touma and the Anglican Church to handing Orsola Aquinas to her, and blindly following the dogma of her Church, such as when she puts Orsola through a mock Trial of Sin. She despises all magicians despite them being present and calling magic as Christian Black Magic, though uses magic as well, justifying her magic as part of her Church's history, and deems all non-Roman Catholics as animals. Orsola references this as part of her doubts and supersitions as being a Roman Catholic, which extends to all of the members of her group.
Orsola references that Agnese actions are based on doubts not on faith and trust. Indeed, after being cornered by Touma, Stiyl Magnus with his Innocentius, and the Amakusa-Remix Style of Church, there was doubt in the Agnese Forces if they could turn the situation to their favor, and doubted Agnese capacity to defeat Touma, whom hesitated with her actions.

She is a ruthless leader when it comes towards enemies of the Church, whose followers has shown to be loyal to her completely, willing to cause mutilation, and beat a defenseless woman for her. Despite her doubts and their faults, she has a kind of trust towards each other, especially to Lucia and Angelene, knowing that they will do their job. With regards to allies from other sects or organizations, she has no problem in deceiving them, giving limited information, and embellishing the truth. Her personality against enemies make her out to be a sadists who loves toying and making others suffer, as experienced by both Orsola and Touma.

Agnese lived in Milan, Italy during her childhood. Her parents were killed for reasons unknown during a very young age, and became a street urchin living on whatever scraps of food she could find. She was later taken in by the Roman Catholic Church along with a number of other girls, where she eventually meets with Lucia and Angelene and became close friends with them. Here, she becomes devoted to Roman Catholicsm, and decides to make the Church the were in more comfortable.
It is unknown how, but Agnese later gains or forms a unique Roman Catholic paramilitary force named after her. A great achievement at her young age, and somehow takes hold of the Lotus Wand.