The title character, she enjoys piloting vehicles and works her first case as a newly licensed C-class salvager at age 16. She has short hair and usually wears red clothes. She is adept at martial arts and firearms. However, her involvement in such outside activities makes her sleep in and habitually late for school despite living in the on-campus dorms across the field. She reacts negatively to and is embarrassed by the broad displays of sexuality that she observes from her peers.According to her character profile, she lost her parents in the worldwide earthquake catastrophe and was raised by Gozo Aida. Her body harbors a secret. E.T.A.I. refers to her as Zero. Aika does not submit to the alien probing like the other girls, and it is revealed that she has some form of alien presence inside her body that allows her to defeat the yellow tendrils and turn them back on her opponent. In a supplementary manga installment Aika Zero Cute, she is a university student.
