Yosuga no Sora

Yosuga no Sora (ヨスガノソラ, lit. "Sky of Connection") is a Japanese romance/drama adult visual novel developed by CUFFS ("Sphere"). The game was originally released for Windows PC on December 5, 2008. It was adapted into a serialized manga and a TV anime series. A sequel/fan disk titled Haruka na Sora was released later on October 24, 2009 which contains new and expanded scenarios for several characters from the original game.
Link Download 
Part1
Part2
Part3
Part4
Part5
Part6
Note : maaf saya hanya bisa berikan sampe part 6... :)