A Gestalt [[Elster (signalis)|]] repeatedly encounters during the events of the game who is searching for her sister [[Erika Itou (signalis)|]].

[spoiler] Near the climax, it's heavily implied that she and her sister [[Erika Itou (signalis)|]] died before the events of the game, and her existence is due to [[Ariane Yeong]]'s Bioresonant abilities manifesting her into reality.
isolde itou