The card I got off Ebay appears to be some sort of promotional item for the set. It's of Daisuke Motoki and has information about Series 4 for the set. It shows the front of the three "regular" cards from Series 4 - Domingo Martinez, Toshihisa Nishi and Koji Uehara. Motoki is one of the "special" cards for Series 4 (along with Yoshinobu Takahashi and Masaki Saitoh) so I actually wondered for a little bit if this was the "special" card. The fact that it is oversized (roughly 8 inches by 5 1/2 inches) kind of dissuaded me from that along with the fact that it has no card number (Motoki's card is #S12). Then I found the real "special" card on Yahoo! Japan Auctions. I wonder if this was some sort of advertisement for the set inserted into the newspaper.
One thing I found interesting is that the back has an advertisement for another BBM set - the Shigeo Nagashima tribute set called "Mr. Giants".