A second year student who plays the euphonium. She is rarely seen talking, and it seems like she has an aloof attitude. It is later revealed that the second-years are like this because there aren't many second-years, due to something that happened in the past.

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.

(Source: Hibike! Euphonium Wiki)