Is this sort of a cameo? This is the vocaloid Hatsune Miku celebrating Sonic's 20th Anniversary by wearing a Sonic themed costume. It's like a hoodie with spikes on over her clothes, and Sonic gloves too. This must be some kind of CD case cover, and she likely sings some of the vocal tracks from some of his games. But which ones? The whole thing is in Japanese so you can't read it.