Aozaki Touko [Person]
The Grand-class doll maker that has appeared in some form or other in a multitude of Type Moon works.
In the Case Files timeline, her Sealing Designation was removed when she made her appearance. However, since a certain ending in Fate/stay night has her described as “Sealing Designated,” that will probably only last for a few more years…
Between things like the special “box” she keeps inside for special occasions, to the crystal familiars she collects that fire beams like a certain little sister, in a story like Case Files where magi are the main attraction, her abilities become even more impressive.
After being given entirely free reign in the Iselma incident, she began to follow the Heartless case entirely out of a sense of curiosity. In the middle of the incident, however, the Neutralist faction commissioned her for a formal investigation. In normal circumstances she would have simply refused the assignment, but at that time the compensation she was supposed to receive from Iselma had been reduced to ash (by her own hands). Oh, what a travesty, doll maker!
Furthermore, due to circumstances, she already had experience visiting the Spiritual Tomb of Albion.
From the start, though only for a short time, the reason for the removal of her Sealing Designation was because Millieune Carillon, head of Sealing Designations and the one responsible for removing her Designation, and her were…

Lord El-Melloi II Case Files material - Encyclopedia: Aozaki Touko [Person], p.096