Priestess of the Alien God

The Priestess of the Alien World (localized as Foreign Priestess and referred to as U-chan by Pepe) is an unnamed woman who appears during the Cosmos in the Lostbelt scenario of Fate/Grand Order. The identity of the woman is unknown. Before Chaldea is attacked, she is shown to be present in the Lost Room. The woman remains silent and mostly emotionless. She is shown to react to seeing Ritsuka Fujimaru's destroyed room by gazing sadly at it, and she reaches her hand out to Mash Kyrielight in the opening. She has since made several appearances during a number of the Lostbelts but her true nature still remains unknown. The woman is shown to be present throughout Chaldea without anyone noticing her. She also completely froze and then shattered the Russian Lostbelt's Fantasy Tree with but a single touch. The instruments of the Shadow Border are unable to detect her presence, instead detecting simply [nothingness] where she stands. Holmes describes her as a void-like emptiness seeping out into the space around it. She can somehow make her existence perceivable only for certain people, proven when, even in the same room, Sigurd in his spiritual form was unable to sense her presence nor see her, falsely believing his master was talking alone.