OniAi (2012)

Original title: お兄ちゃんだけど愛さえあれば関係ないよねっ

Adorable young Akiko is thrilled to be reuniting with Akito, the handsome older brother she hasn’t seen in years! In fact, she might be a little too excited about living under the same roof with her precious big bro. This pint-sized cutie has a serious brother complex, and she’s definitely not interested in sharing his attention. Unfortunately for little sister, she and Akito won’t be living alone: three gorgeous girls from the student council will be along for the ride! So much for the peaceful existence Akito was craving. Big Brother the dreamy will have to stay on his toes to avoid the advances of Sis and her ravishing rivals!