Too make it easier you should open winrar and change it to zip and .oskElzapatoverde wrote:
Ok, you need to extract the rar file (with winrar, 7zip or other app) an then drag the folder named "Kagerou Project" into the Osu's Skin folder (you can find it in C:Program Files osu!Skins).
If you have any questions do not hesitate to ask ^^
P.s. this is directed to the skin creator