On my latest trip to Yokohama, I stopped by the card store to do a bit more "research" and pick up a few cards. They have "team packs" repacks for several NPB teams of varying thickness. Each pack has an insert or parallel shown on the front and back, and they consist of cards exclusively from a single team. I bought two, for two different teams.
The Marines pack below had 31 cards.
The Kishikawa card was a bit of a surprise. I rarely see older cards at card shows and I didn't expect them to be in here.
You can see that there are some foreigners included in the packs, which will hopefully help out with my collection.
For 150 yen, I'd say I got my money's worth just with the Stats Leaders card - inserts in Japan start at 200 yen ($2). The other premium inserts, subset cards, and other player cards I needed in my collections just added to the value! And at 5 yen per card overall, it's only 1/8th the price of normal common singles at stores!