Natsuki is a young girl who wears the standard Kitauji High School uniform for second years. Her auburn hair is tied in a high ponytail, two strands sticking out from it, and she has blue eyes.
Natsuki is a reserved girl who is seen rarely talking, and she has an aloof and calm attitude. It is later revealed that the second-years are like this because of an event which occurred the year before Kumiko Oumae's first year at Kitauji.
However, Natsuki is normally friendly to everyone, and tends to be mature and calm in most situations. She is also understanding of situations and takes everything quite nicely.
- She and Yuuko often get into playful arguments and teasing, much to the amusement of others, particularly Kumiko.
- She did not pass her audition.
- Natsuki, Yuuko, Nozomi and Mizore graduated from Minami Junior High School.
- Natsuki joined the band because of Nozomi as she admires her.
- Natsuki has short hair in the novel and manga.
- Natsuki used to not have any illustration in the novel so her appearance in anime version is completely redesigned. Character Designer Shoko Ikeda said Natsuki looks awful with her short hair like in the novel so she made her hair a bit longer and put her hair in a ponytail so she would look cuter. Natsuki's illustration is revealed on the cover of the new novel series , which shows that her appearance in the novel is now the same as in anime version.
- Natsuki becomes the band's vice president in her senior year.
- According to the official Sound! Euphonium novel website,
- Her favorite colors are purple and black.
- Her special skill is being able to perform fast calculations, but is still poor at math.
- In the novels, Natsuki's euphonium case has a yellow, faded bear charm key-chain on it.
- Natsuki's euphonium is based on a Yamaha YEP-321 model.