I've seen that one put here on a forum before, actually, and I personally believe that the Tamagotchi is a fake, but that is because the paint job seems to be off and such, as well as the back of the Tama, the rest button is off and the insides look strange to me, as compared to others.
However, I have only ever had a Familitchi and the Music Star, as well as the Japanese Ketai and Ketai Akai. So, I've never looked inside the american v2, v3, or v4, which one of these I think has the same antennae. So, I could totally be wrong.
But don't let the beaded part through you off dear, there are some Japanese Tama's that come with the bead portion, and my Japanese Tama's don't come with Key rings either. Mine have a small clip on piece that clasps onto things.
Well, I hope that you get better answers than what I have to give XD later
-Ki