You mention finding cards that have not been catalogued. I assume (like all non-Japanese collectors) you rely on Gary Engel's work as a resource. But in your time in Japan have you ever come across a Japanese language version of a catalog? In several years of reading and collecting Japanese cards, I don't recall anyone mentioning it. So do Japanese collectors rely solely on BBM (the magazine) as a reference source?
I ask only out of curiosity since being Japanese illiterate such a catalog would be of no use to me. I'm just asking to get a better understanding from the Japanese collector viewpoint (and your descriptions of card shows there in Japan was very informative from that standpoint as has your blog been overall). Is Engel the only person (Japanese or foreign) to publish a comprehensive resource?
I thought this was important enough to address here. I'm going to expand on the question for those who aren't as "in the know" as other collectors of Japanese cards.
I do rely heavily on Engel's catalog as a resource. I have the 7th Edition, which owners know is complete through early 2008. It's proven invaluable in identifying cards, and even just knowing what's out there. The same could be said for the almanacs issued by Beckett and SCD. There are errors and omissions, and the prices aren't always accurate. However, I think the disclaimer in the guide is pretty accurate about prices: "...the price for each card listed in this Guide now reflects the retail value in the U.S. or Japan--whichever is higher." And retail value is just like the HI column in Beckett, what the highest price you could expect to pay for the card at a store in Japan or the U.S.
As an example, most BBM commons are listed at 50 cents in the guide, which essentially is 50 yen in Japan. When visiting most card shops in Japan, singles start at 50 cents, so this "base" price is pretty accurate. There are some shops that have singles starting at 30 yen. Most stores price older Calbees starting at $1 (for the 1990s) or even much higher for cards in the 1970s and 80s, but look around enough and you'll find them far below "book" price.
So, now, what else do I use as a source? When it comes to historic cards, I have yet to find another source. Actually, I really need to update to the 8th edition of Engel's book in hopes of identifying some of these other oddball cards I have in my collection.
NPB Card Guy's site (Japanese Baseball Cards) is a big help for more recent cards. It's not a guide or a complete listing, but sometimes I can identify a set's name through his descriptions. The SCF Set List Inventory has also helped a bit, though it's incomplete after 2007 (due to the lack of a full source).
Calbee's website has a complete checklist (excluding parallel information) on their website. This certainly has come in handy in creating lists for sets over the past six years. It only goes back to 1998 and is in Japanese, but with a little bit of work I can figure stuff out.
There is a Japanese Sports Card Forum website which has a lot of information about autograph and memorabilia issues, though it's hardly complete.
Now, to address Greg's main question: Are there any other comprehensive guides beyond Engel's?
The Japanese market for old cards is almost nonexistent, and as with almost everything in Japan, only the "best" is worth collecting, which is Calbee and/or BBM. Card sets issued for gaming (CardGen, BBH, etc) and by other manufacturers (such as the OB sets by Epoch) are generally considered second-tier, much like Panini's cards are without logos. So these cards just don't get cataloged in Japan. The same goes for team issues, promos and special issues, and other minor sets.
In my quest to reach (as close to) 100% on a Japanese type collection, when I find new cards I do my best to identify them. But I don't have the time, resources, or knowledge to really determine manufacturers, dates, or anything else that isn't included on the actual card. Once I get myself fully organized, now that I'm over 50% completion of known issues, I hope to start reporting on what I've found. While Engel's guides provide the most-complete information, including prices, for vintage sets, I'd like to expand on the information and catalog the current issues as well. My "Cardboard Zoo" blog might be the location for that, or an entirely new blog might be created. Or I could post it here. It was one of my goals to start posting Calbee set information this year, but there just haven't been enough hours in the day!
If anyone has come across another comprehensive guide to Japanese baseball cards, either in print or online, in English or in Japanese, please post about it here!