Takanashi Sora

The eldest of the three half-sisters. She is a second-year middle school student, and has a tsundere personality. She has fairly good grades in school but is not adept at cooking. She has had a crush on Yuuta since they first met but starts out calling him "oji-san (uncle). When they become more comfortable with each other she starts referring to him as "older brother (Onii-chan)" even thought they are not, strictly speaking, related. Yuuta is (perhaps purposefully) oblivious to her feelings.