I have recently bought one of these on eBay, which arrived little over an hour ago. I too was a little concerned it might be a fake. The back of the shell looks almost exactly like the picture already posted, only the sticker was all in English. I was also concerned because all the pictures of V4s I have seen have a "Digimon" style keyring, whereas mine has the one that the original Tamas had.
The only difference was the packaging. This is a picture of my Tama taken from the eBay auction page.
Picture
Can anyone kill that last bit of doubt in my mind that I have a fake?
Edit: Futhermore, I think it might be a V4.5, because it has just grown into a Kuchitamatchi!