Nee, Chanto Shiyou yo!(2005)

姉[ねえ], ちゃんとしようよっ!

When Kuuya's parents died, he was adopted by the Hiiragi family. In a household of six elder sisters, he was the only guy. In time, he fell in love with his sister Kaname, but their father noticed and was worried about what it could become so he sent Kuuya to his distant relatives. Now Kuuya has decided to return and pay a visit to his sisters, who are more than pleased to have him back—at least, most of them...