I found a few of these sets in Mint Sapporo's display case, discounted to 300 yen each. I grabbed one for myself.
Originally retailing for 1200 yen (about $12), this 18-card set was originally intended to be distributed at Kamagaya Stadium on March 16th, though the earthquake canceled the game. Sets were then made available to the public. Only 3000 sets were apparently issued but the set doesn't contain any big hits to chase after.* It was issued in a small blue-background box, with the Future Icon logo and "Kamagaya Stadium Edition" printed near the bottom. All the players are Fighters, and given the name of the set, they must be rookies or younger players.
NPB Card Guy's post. Cards 10-16 have biographical data; a blue background and a player headshot replace the puzzle image. 17 has a blackish background, sepia photo from the front, and biographical info. Card 18 is a checklist with the same blue background as 10-16.
*While there are no chase cards advertised on the box or visible after a cursory search on the web, it seems that Cubby has some autographs in the set (possibly facsimile), and NPB Card Guy reports that there are possible autographs of Saitoh. It might be one special card with autographs of Saitoh and Cubby; the translation is sketchy.
NPB Card Guy confirms that no other sets were issued (see the comment below) but I wonder if similar sets were planned at some point. And I would like to see an image of the autographed Saitoh/Cubby card(s).