Found this site, it looks like it's Chinese? For some reason there's no photos on the blog. Translated to English. https://www-hifiwalkman-com.translate.goog/?_x_tr_sl=zh-CN&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc
This Korean Site looks promising, for some reason I can't get beyond the main page without going through google search, but then I can get some of the other pages to show up. http://d-noz.com/
I finally obtained a Sony ZX-7 that @Valentin is helping me improve online, since W&F are a bit on the high side. Any additional information on this DD boombox would be greatly appreciated! Edit: I know this is a ZX-3, given the slightly different button placing and the telltale handle
Some of the rare ones don't seem to get any press! If you're in Japan and can get on the amazon.jp Kindle Service you can view a ton of JDM Magazines and Books online. I tried a few different ways but I think you need a Japanese CC for verification (and to pay). I think you can still see a page or two in the preview mode, maybe do some research through that. I've found two issues of Popeye, The Magazine for City Boys, that always has cool ads and is neat to look at just for the consumer products and clothing. Some Japanese Magazines are on archive.org but searching for those is hard with the different languages. The ZX-7 is a nice pick up, super small and heavy, what color is yours?
An article on the Design Underground with some neat photos, I looked for it two years ago but I think it was closed? https://lovely-lovely.net/business/dug-factory/ and another with some cool photos https://intojapanwaraku.com/culture/75832/
There's a boombox page and some other neat electronics https://nationalmaclord-web-fc2-com Two CDs, Two cassettes and TV stereo, what's not to like about this top-of-the line Sharp QT-83CD?
For some reason I can't get this to translate, they do have some portable CD players and other stuff. These sites tend to disappear http://www.sutafuya.net/top.html Here's the PCDP blog attached to the site http://www.pcdp.sblo.jp/
More stereo equipment, I didn't go through all of it. Check out this monster Sony SS-G7 Driver, I bet this isn't easy to move around. http://blog.livedoor.jp/johnny_trio_lsr/archives/2091550.html
There's some early Walkman Pages on this blog. Love the Check Cab, I used to go to the factory when I was a young delivery driver. https://appletechlab.jp/blog-entry-1338.html
Repairing a crusty DD-9, there's some other cool Japanese Products on this site. https://zigsow.jp/item/361135/review/371662
There's still some cool sites left. My advice is to download the entire site, there should be some programs still around to grab everything. 20+ years ago there was new site/blogs popping up daily but most were on free web-hosting. Years later they shut down and we lost so much great information. Some of these have link pages, go through all of those, there might be more nuggets down there.
A little off topic, I just browsed through the cool photos, you know I love Mazinger Z, I have three of the large figures. https://mag.japaaan.com/archives/139127/sub1-613
There's a National being tuned up, I didn't read it yet but there is also some other boomboxes on here https://av.watch.impress.co.jp/docs/review/review/1524780.html