Haruno Yukinoshita

Haruno is Yukino's elder sister who is even more outstanding than Yukino. However, unlike Yukino, she shows a good attitude towards other people, even if she has to lie about her true feelings most of the time. While Yukino holds strong animosity towards her, Haruno sees her sister who's constantly trying to overtake her as cute. She is a former student of Sōbu High School.

Source: Yahari Wiki