Akitsu

秋津

Akitsu is a 'disused' Sekirei, whom Homura calls 'Scrap Number'. She cannot be winged by an Ashikabi or use the Norito, making her useless from MBI's perspective. Her power is very strong, enabling her to fight on par with Sekirei like Homura; they have met three times so far. Although she cannot be winged, she regards Hayato Mikogami as her Ashikabi because he took her in, and she fears being discarded again.
Akitsu possesses a cold and melancholic personality, much like her power. She speaks rarely in a neutral tone and seems forgetful, as it was once noticed she wore no panties. Initially, it was assumed Hayato Mikogami had ordered this, but she later revealed she simply forgot to put them on. She also expressed envy toward Homura, since he could still be winged and thus have an Ashikabi, a state she can never attain. Additionally, she appears polite and follows orders without hesitation.
Akitsu also seems to possess knowledge regarding subjects such as the first generation Disciplinary Squad.
(Sekirei Wiki)