I had a bunch of questions about BBM's "Light Packs" in the comments of this post the other day, so I thought I'd devote a post just to them.
In 2003, BBM introduced the "Light Pack" for the 1st Version set. Instead of being a pack of 10 cards for 200 yen, the "Light Pack" was a pack of 5 cards for 100 yen - half the cards for half the price. Each pack contained one parallel issue "kira" card - identical to the original card except it was shiny and sparkly (and had a ginormous baseball added to the background). In addition, the "Light Packs" contained insert cards for the 2002 MVPs (Hideki Matsui and Alex Cabrera) that were not found in the standard packs. The insert and memorabilia cards that were inserted in to the regular packs were not available in the "Light Packs". To further complicate matters, only cards 1-405 of the 432 card 1st Version set were available in the "Light Packs" - it was impossible to get any of the cards in the "2002 Retirement Player" (cards 406-420) or Team Checklist (cards 421-432) subsets in the "Light Packs".
When BBM issued the 2nd Version set later in 2003, it again also issued "Light Packs" for the set. The regular 2nd Version packs were 9 cards to a pack - the "Light Packs" were 4 cards to a pack - a little less than half the cards at half the price. Again, each pack contained one "kira" parallel issue card and again there were insert cards for the 2002 MVPs that were not issued with the regular set (and were not the same as the ones for the 1st Version "Light Packs"). However, "kira" versions of the 2nd Version insert cards for the regular packs - "Opening Game" and "Record Achievement" - were inserted into the "Light Packs". And again, only a subset of the regular set was available in the "Light Packs" - cards 805 to 839 (the "New Wave" and "2002 Retirement Player" subsets) do not appear. And also again - the memorabilia cards available in the regular 2nd Version sets are not available in the "Light Packs".
Here's an example of the regular and "kira" card from the 2nd Version set (Takuro Ishii #606):
I can speak with some confidence on the 2003 "Light Packs" because I actually had a box of them for each set. All I know about subsequent years is what I can glean from Gary Engel's "Japanese Baseball Card Checklist and Price Guide". It appears that BBM did "Light Packs" for both the 1st and 2nd Version sets through at least 2007 (the last full year in the book) and for all I know they continue it to this day. Regular packs have contained eight cards since 2004 and the "Light Packs" have contained four. It looks like the "Light Packs" have continued to have one "kira" card parallel issue per pack (although for the 2007 sets, Engel describes this card as "metallic" rather than "kira"). It also appears that BBM has continued to have the previous year's MVPs on insert cards that are exclusive to the "Light Packs" (although again 2007 was different - the "Light Pack" inserts were for "Speed Stars" - Tsuyoshi Nishioka and Norichika Aoki). Additionally, in 2004 and 2005, there were "kira" versions of 2nd Version insert cards in the "Light Packs". Since I was only sure that the 2003 "Light Packs" only contained a subset of the set by looking at the checklist on the back of the box, I don't know if those in subsequent years also only contained a subset.
The image at the top of the post is for a 2003 1st Version "Light Packs" box. (You can see an image of the regular box here.) The other image is of the wrappers from the regular and "Light" 2nd Version packs (which would not sit straight on my scanner).