IMOUTO WA SISCON ANI GA MENDOKUSAI

Yui Hasegawa, an unattractive high school student, has an older brother, Yu, who is both a literary and martial artist, cool, and called the most handsome guy in school. The two are so unlike each other that it is hard to believe they are brother and sister. There are even rumors that they don't get along, Yui, who has a "perfect brother," is troubled. It is...the fact that her brilliant and talented older brother is actually a severe siscon. A hilarious home comedy about siblings who are complete opposites! — Description from AniList community (anilist.co).