Aoi Doumeki, adopted into the Doumeki family at five years old, is the younger adoptive sister of Chikara Doumeki by approximately five years. She possesses a slim build, short brown hair, and notably wide brown eyes. Her consistently depicted androgynous appearance led Nanahara to initially mistake her for male during their first encounter. Following her adoptive brother Chikara's departure from the family, she actively sought him out to reestablish their connection.