Asuka is portrayed as a young woman of above-average height with straight, shoulder-length black hair and light blue eyes. She wears thin red circular glasses, which are considered her trademark. Many characters, including Hazuki Katou, regard her as exceptionally beautiful.

Outwardly, Asuka has a playful, friendly, and caring personality, so much so that her constant high energy often comes across as childish to the other band members.

However, her humor and lighthearted demeanor are a facade that conceals deeper emotions she has suppressed for years, many of which stem from her mother’s strict parenting and from having all contact with her father cut off. Beneath her bright exterior, Asuka is far more sly, calculating, and coldly logical. When necessary, she can be pragmatic, manipulative, and somewhat self-centered, though she is not a bad person by any means.

Asuka first appears when Hazuki Katou, Kumiko Oumae and Sapphire Kawashima enter the band room for the first time, where they see many students and Asuka herself playing music. After chatting a little, Asuka approaches them and surprises Hazuki with a kissing face, making Hazuki trip and fall in shock. Then, Asuka opens the door and asks if they are coming to visit. After Asuka introduces herself properly, Hazuki decides that Asuka is very beautiful.

Asuka first appears when Hazuki Katou, Kumiko Oumae, and Sapphire Kawashima enter the band room for the first time. They find many students already playing, including Asuka. After a brief moment of observing, Asuka approaches the trio and startles Hazuki by leaning in with a playful kissing face, causing Hazuki to stumble backward in surprise. She then opens the door, cheerfully asking if they’ve come to look around. After properly introducing herself, Hazuki immediately concludes that Asuka is incredibly beautiful.

During the first level of competition, Asuka appears downcast onstage and post performance due to her knowing that her mother will not allow her to compete in the nationals, something unknown to her peers.

In the first half of the second season and in the second light novel, Asuka learns that her father, whom she has not seen since she was very young, will be judging the final round of the competition. Now that she has the determination from her father to continue striving to perform, Asuka begins to behave in extreme ways. The most notable instance of this is when she tries strongly to forbid Nozomi Kasaki from rejoining the band, fearing that the sour relationship between Nozomi and Mizore Yoroizuka, a player in the band’s musical success, will affect Mizore’s performance ability.

In the second half of the second season and in the third light novel, Asuka is forced by her mother to quit the band but eventually manages to return in time for the final competition, at which she receives the first contact from her father in many years.