Altera (Moon)

This mysterious sword-maiden in white, a Saber-class Servant, bursts onto the scene from the Zero Dark.
One of the three main heroines of EXTELLA. She is also one of the only three Servants to have a Master.
Her backstory runs deep, so please see the “Titan Altera” entry for more information.

Fate/EXTELLA material: Encyclopedia of Fate EXTELLA