Asuka Koukawa (甲河 アスカ), is Asagi's adopted daughter, a prodigy and rogue Taimanin. She is currently a member of the DSO.

Asuka is a Gal who is mostly happy and energetic, usually joking and saying how cute she is, not wanting anybody to get mad at her when she messes up, which she often does. She also has a bad temper, and that gets the best of her. She has a competitive drive and doesn't want to lose to others. She is upbeat and self-confident in her strength, which often leads her to appear careless. When she does mess up, she usually smiles. She is impatient, and tends to rush things, causing her or her equipment to be in danger. She likes teasing others but only when she really likes them. She often makes a show of it, overdoing everything, be it movements or her voice. Asuka doesn't like losing to others, whether that be in combat or games. If she does, she can get angry and whiny.

Asuka hides her fears beneath a confident facade. She has a fear of abandonment and being left alone; she doesn't talk about it unless pressed. She is afraid of the possibility of being cast aside if she were to make a mistake, or of having her current form taken away from her. When talking about her past and her former self, she will be more distant and calm. The subject depresses her, and she will try to cover up any hints of weakness she might reveal, acting like nothing is wrong.

She bends the rules, she is willing to use lethal force if needed, and she isn't above using her appeal as a weapon, if it gets what she wants. She is a believer in the Taimanin ideal of justice, and unlike some Taimanins, she rather acts as a rogue to have her freedoms. She can be persuaded to team up with criminals, if it's necessary.