Imouto wa Siscon Ani ga Mendokusai

Yui Hasegawa, a somewhat lackluster high school student, has a cool older brother, Yu, who is a scholar-athlete and the most handsome guy at the school. The two are so completely dissimilar that it's hard to believe they are brother and sister, to the point where there are rumors circulating that she doesn't get along with her "perfect brother." As for that... her accomplished and handsome brother is actually a severe siscon...! An uproarious home comedy about siblings who are polar opposites!?

(Source: Ichijinsha, translated)