Nonomiya Ai

Ai is Kanata’s non-blood-related imouto who came into his household when Kanata’s father remarried Ai’s mother. Besides that, she is also the super bracon genius viola player who says some of the most darnedest phrases ever uttered by an imouto. She shows no shame being a bracon, and proudly declares Kanata to be a siscon despite his protests. Underneath that, she is also deeply caring for Kanata and will do anything to help her onii-chan since they are each other’s only family.

Taken from Aedes' review.