The set contains 90 cards. The first 19 cards in the set are for the 2013 team and feature most of the better players on the team such as Atsunori Inaba, Shinya Tsuruoka, Shohei Ohtani and Daikan Yoh as well as manager Hideki Kuriyama. I was a bit surprised to see Yuki Saitoh included as he barely played at the ichi-gun level this year but I guess BBM decided that he was still popular enough to have him in the set.
The next subset is three cards labelled "Great Sensations". The three people so honored are Trey Hillman, Tsuyoshi Shinjyo and...Yuki Saitoh. *SIGH* I know I said I wouldn't make fun of him anymore but sometimes BBM just makes it hard...
The next subset is "Historic Highlights" - the 14 most significant events in the Fighter's 10 season in Sapporo, arranged in chronological order. They are the first home game on 4/2/2004, Shinjyo's retirement announcement on 4/18/2006, winning the pennant in 2006 (first pennant for the Fighters in 25 years), winning the Nippon Series in 2006 (first championship since 1962), Yukio Tanaka's 2000th hit (5/17/2007), winning the pennant in 2007, Makoto Kaneko going seven straight games with a double in 2009, clinching first place in 2009, Terrmel Sledge's game winning grand slam in the Climax Series in 2009, Hisashi Takeda's 52 consecutive scoreless inning streak in 2011, Atsunori Inaba's 200th hit (4/28/2012), Hirotoshi Masui setting a record for most holds in 2012 (I think), winning the pennant in 2012 and Shohei Ohtani homering in a game that he was the winning pitcher in this past season (7/10/2013).
There's one last card in the set - a checklist card showing the Fighters' three mascots.
It may not sound like it, but I actually like this set quite a bit. Generally I don't think BBM's Anniversary sets cover specific highlights in a team's history as well as this set does. I'd like to see more of that sort of thing. Really the only way this set could be better is if it had Yu Darvish in it instead of Yuki Saitoh.
You can see all the cards at Jamabalaya (and I will admit to leaning heavily on the translation of their card descriptions for the info on the highlight cards). Ryan has also done a post for this set.
UPDATE - I neglected to mention that this is the first team-based OB set for the Fighters. Now the only team that has not had any sort of anniversary set done for it is the Eagles. I'm betting that since next year will be the Eagles' tenth season, BBM will be doing a set for them.