Song: hiyoku no sora
Instrument: piano
Anime/Game: yosuga no sora
Artist: efonius
Album: -
Comments: this song was good (for me) and i want to know the piano sheet for learning piano. please. :cry: i don't get it from google.

I haven't personally taken a look at these sheets, but:

http://ingsmusica.blog41.fc2.com/blog-entry-22.html (click on large red ここ under the video)
http://www1.axfc.net/uploader/File/so/54861 (password that goes into text field beside キーワード: okukosome)
http://www1.axfc.net/uploader/Sc/so/224292 (same deal as above, password/archive pass: tanafile)