Natsuka has black hair which almost appears to be blue. Fittingly, her eyes are blue as well. Under her mouth, a black mole can be seen. She wears a light red pin on her right bangs. As a Sakuragaoka High School student, she is usually seen wearing the school's uniform properly with black socks.
In the second chapter of Volume 4 of the manga, a member of Class 3-2 called Sakurai (桜井) was a candidate for the second leading role of the class play "Romeo and Juliet". The anime adopted the name and invented the actual character, as Natsuka can't be seen in the manga.
Both in the manga and the respective anime episode, Natsuka managed to get four votes.