Kazumi Aihara

She is quiet, mysterious, and somewhat sadistic. She is often seen taking notes down in her observational diary on whatever happens to interest her at the time rather than participating in physical activities along with everyone else. However, no one, not even Chika whom she has been friends with for a long time, has ever seen her laugh. Like Ryouta, she is a member of the health committee. Her number on the class list is 1.

(Source: Wikipedia)