The set I posted about yesterday, featuring Kenta Maeda, is just one of many in a series of single-player releases by Sports Graphic Number (or under the Sports Graphic Number name). I believe this is the first baseball issue they printed, issued in 2011 and featuring Shinjiro Hiyama.
The Special card set is split into three subsets of nine cards each; future releases have two subsets. The checklist distinguishes each subset. Each subset also assembles into a puzzle.
Because I don't have the second checklist and it's not listed in any guides, I'm not sure about any rare cards such as autographs, relics, or photo cards. The other checklist is on my want list right now so I can update this post sometime.