Aoi Yusa

Fitting her appearance, she has a rather childish or better yet a strange personality. Aoi, on the inside, is shown to be a kind, polite, and a very hard-working individual, and is very grateful to those people she has high esteem for, especially Kodaka. Though she acts cold, and rather brash, to those individuals whom she believes have wasted potential, and for people who disregard their duties[...]. Source: haganai.wikia.com/wiki/Aoi_Yusa