Enigmatic and androgynous, Subaru was another member of the short-lived European Hoshigumi alongside Lachette Altair. She is acknowledged as a genius, and said to have never been defeated in any form of competition or combat. As such, she tends to come off as a little arrogant and looks at everything in an analytical sense. Thus she takes an interest in things that she cannot comprehend completely such as Taiga Shinjiro's charisma and the concept of jazz music. Because of her looks, the others often wonder if Subaru is male or female, in which she responds that "Subaru is Subaru" and that gender is not important.