The bulk of the Lions team issued cards were from a set that I was able to date to 2007 (and I'll explain how in a moment). This was kind of a unique set as usually with modern baseball cards it's obvious which side of the card is the front and which side is the back. The front has a picture of the player and the back has the player's stats and/or biography. However I can't decide which is the front and which is the back on these cards. Here's one side of Fumiya Nishiguchi's card from the set:
Here's the other side:
Both sides have the player's photo and name (it's only in Kanji on the portrait photo side) and neither have stats or biographical information. I've put them away in my "Team Issued Cards" binder with the portrait side "up" but I could have just as easily done it the other way. Here's some more cards from the set - the portrait will be first for each player:
The 24 players I got were Shogo Akada, Chris Gissell, Taketoshi Gotoh, Alex Graman, Hiroshi Hirao, Kazuyuki Hoashi, Tomoki Hoshino, Toru Hosokawa, Ming-Chieh Hsu, Takashi Ishii, Tetsuya Iwasaki, Masahide Kaizuka, Junichi Kawahara, Takayuki Kishi, Fumiya Nighiguchi, Kosuke Node, Koji Ohnuma, Eiji Shotsu, Ginjiro Sumitani, Hiroyuki Takagi, Yasuhiro Tanaka, Yuya Tazawa, Kazuhiro Wada and Satoshi Yamazaki. I assume there are other cards but I don't know anything about them.
I was able to date the set to 2007 as that was the only year both Kishi and Wada were on the Lions. Kishi was a rookie that year and Wada would leave for the Dragons after the season ended.
The Lions had a set the previous year that used a similar design to the non-portrait side of the 2007 cards. Here's the 06 and 07 cards of Eiji Shotsu to show the similarity: