http://en.wikipedia.org/wiki/Kousuke_Yamashita
This is the guy who did the rearrangements/compositions. He did Gokaiger!
Also, it seems that the cover was done by an artist from pixiv (like Japanese deviantArt but awesome) and Kaikai Kiki (a service for artists started by Takashi Murakami). Keep in mind that the cover really is an illustration and is not just the original photo processed in a program.