The first batch of cards had been published in SCM #50 which came out in March of 2005. There were cards of five players issued with that edition of the magazine - Hisashi Iwakuma, Munenori Kawasaki, Hiroyuki Nakajima, Michael Nakamura and Ryota Igarashi. The Nakamura card was a bonus card for the 2005 BBM Rookie Edition set and the Igarashi card was a promo for the Swallows team set. The other three cards were an original design for SCM. SCM cards usually have some sort of parallel version and I somehow got the gold signature parallels for all of these cards - I think the auctions were for several "hot packs" of all parallels as this wasn't the only issue that I got parallel versions of all the cards. Here are scans of all the cards except the Nakamura card - I already had it and if you're interested, you can see it here.
The next issue I got the cards from was SCM #51, published in May of 2005. It included two cards commemorating the first inter-league games ever in early May of 2005 (which means the cards got turned around in just a couple weeks as the magazine was published at the end of that month). Again I got the signature parallels for the cards:
SCM #56, published in March of 2006, contained cards for five players who had changed teams over the winter. Three of these players were returning from North America - Norihiro Nakamura, Kazuhisa Ishii and Shingo Takatsu. The other two were essentially traded for each other - that winter Kiyoshi Toyoda left the Lions as a free agent and signed with the Giants, who sent Akira Etoh to Seibu as compensation. It may not be obvious at first but these cards are also parallel issues - the regular cards have white rectangles at the bottom, not yellow.