Shirabe is one of Fate's many pactio partners and like the rest of the girls she has romantic feelings for him.
One of Fate's Ministra magi, she has a very serious and composed nature, and is often seen with her eyes closed shut.
Shirabe and her tribe was hunted, due to racial conflicts between humans and demihumans. Seemingly the only survivor in her tribe, Shirabe was cornered before Fate and Shiori/Luna appeared to rescue her. Shirabe then began working alongside Fate, taking up his proposal to "change the world." Because of her past as an orphan, she appears to resent the more privileged lives of Negi's teammates.
Shirabe first meets up with Negi's party during the Ostia Festival. Haruna, Chisame, and Nodoka (whose artifact reveals her true name as Brigitte) are able to counter her attacks, but the girls eventually succumb to her power. Cornered, they are almost defeated until Kotarou intervenes and allows them to escape.
She later appears alongside the rest of the harem at the Governor's Ball to battle Rakan. She reveals her true form as a wood sprite, but is still easily defeated within minutes. She is later seen in the Gravekeeper's Palace, monitoring the progress of Negi and company upon their arrival. She stays behind to help Fate with the rewrite ceremony and does not join the rest of the girls in their fight against Ala Alba. However, a surprise attack from Kotaro and the others renders her unconscious. Upon their defeat at the hands of Quintum (with Fate, upon defeating Quintum, reclaiming the Great Grand Master Key and Asuna while capturing Nodoka and Natsumi as well), she awakens and continues assisting Fate in ceremony. Once Negi began fighting Fate at the site of the ceremony, Shirabe was tasked with bringing Asuna's body to the altar, as doing so would prevent any human in the Magic World to be stuck on Mars once it's completely destroyed by the ceremony. Despite attempts to stop her by some of Negi's students, Anya, and the combined effort of Takane, Mei, and Collett, Shirabe, using her plant control skills, was able to follow through with the plan and place Asuna on the altar.
- Fidicula Lunatica: A violin-like artifact which can produce sound waves that destroy everything in her sight. Her artifact looks like a normal violin and apparently she can't play it well. Despite that, the damage caused by this attack is enormous, as she can destroy half a stone tower with just one blow from her violin. Findicula Lunatica means "Madman's Fiddle".
- Kyrie: Appears to be a basic attack from Findicula Lunatica -- a soundwave powerful enough to reduce stone to dust. Kyrie is the name of a hymn, and is sometimes the first prayer in a Catholic mass.
- Tree Spirit Possession Ultimate Manifestation: Tree Dragon Summoning: A technique she uses against Jack Rakan that allows her to grow large, wooden, dragon-like wings and extends her horns to a longer length. She can control trees and plants, sending large vines and branches to attack her opponents. She is also able to use this ability outside her true form, as it was first seen when Brigitte attempted to bind Kotarou with her vines.
- Her codename, Shirabe, means "melody", referencing her artifact. Her real name is Brigitte.