Kyoudai hodo Chikaku Tooimono wa Nai

Ane (older sister) is uber perfect; she's beautiful, intelligent and is admired as the president of the student council. But, when it comes to her little brother, she goes nuts, unable to control her over-the-top obsession with him. Their days get even more chaotic surrounded by a bunch of oddballs, from a mentally-disturbed best friend, their little sister with a sister complex, an ex-punk convenience store manager, a hardcore masochist, a loli-con and more! Casual comedy perfect for filling your spare time.

(Source: Manga Box)