The gif and mus files come in .zip format. Usually Windowsor OS X can open this without a problem, but you might need an unzipping program of some kind such as WinZip. The pdf files can be viewed using Adobe Acrobat Reader or FoxIt Reader.
To view, transpose and print MUS files (inside the .zip files), download Finale Reader for free.
Yosuga no sora
Kioku (Transcribed by Melkyr)
Piano | pdf | midi |
Komoriuta Ja Nai No Ni (Transcribed by tree_kun)
for Viola | pdf | mus | midi |