A member of the Holy Royal Guard who has entered the labyrinth in search of Asella, apparently concerned for Asella's well-being.
Currently nothing more is known about her.
If you are playing as Asella you will not encounter her - instead you will meet Rhiannon.
The game keeps track of your relationship with Lumina, but for now said relationship has no effect on the game.
Her sword is a visual copy of Caliburn from the Type-Moon series.