Research - my journey
The best option for understanding the detail of any camera is a hands-on inspection, but this is often not possible. Simply looking at Internet images can reveal information: mainly the specification differences between models (lenses, shutters, features, aesthetics, etc). The best places to view cameras are:
1) WorthPoint.com - a record of sales data for antiques, vintage and collectable items, sourced from a diverse group of auction houses and online marketplaces (including eBay). Cameras are grouped under the category "Tools". This site is far better than auction sites because its content is cumulative, while auction sites provide a snapshot of current/recent activity.
2) Yahoo Auctions Japan - an eBay alternative, but with much larger numbers of (home market) Japanese cameras listed. Like eBay, there is the option to switch between items for sale, and those recently sold.
3) eBay - no explanation required (other than look at items for sale and those recently sold).
4) Internet image searches - these never seem to be very fruitful, primarily because sets of images, rather than a single image, are necessary to observe a camera from several angles.
Mike Butkus appears to have a monopoly here. Manuals are sometimes good for technical data, although most were written from a user perspective and for a single variant within a range, rather than as a generic manual covering all model options.
I have a page on third-party books that either contain, or might contain information about Beauty cameras. The gist of my research is that I have found nothing illuminating.
1) The Internet Archive has proved very useful. Select "Books", and "All text" as you progress to the search page, and then set the search to "Text content" rather than "Metadata". The downside to this Archive is that its content is very USA focused (with a bit of India).
2) Google book search can find different results, but these also have a narrow geographic (USA) focus. Select the search option "More", then "Books". Before searching select the option "Full view" from the "Any view" menu, and then filter the results to look at books, magazines, and newspapers separately.
Dedicated websites & Blogs
The only encyclopaedia-type website I recommend is Camera-wiki (that is to say, I actively discourage the use of alternatives). Camera-wiki is run by a group of dedicated enthusiasts, diligently maintained, and the vast majority of contributors take great care to validate the accuracy of the facts they publish (I am an editor). The information isn't always 100% accurate, but it's the best place to start to gather details.
Information from elsewhere has to be regarded with a little suspicion, and tested to establish that the author really does have a unique depth of understanding. A lot of sound-bites get copied from elsewhere, and many personal websites merely paraphrase other websites. I have very happily included links to other "personal" Beauty web content that appears well informed, including a number of Japanese websites and Blogs with good information ... which brings me to the next topic.
There are several language barriers to overcome. The first is a problem with the name "Beauty", and the second is foreign languages.
1) I'll deal with this quickly, because it's a moan rather than a constructive comment, but the word "beauty" returns all sorts of unwanted search results. Even when used in conjunction with the filters of an auction site, 80% of cameras found are those described as "a beauty", or "beautiful" rather than the make Beauty.
2) The most logical place to look for information on a Japanese camera is Japan. Thankfully, today's Browsers provide at-a-click translations. Some are excellent: others not so good. However, to search effectively for non-English sources, it's necessary to search in a different language, and use an alternative search engine. I've had a lot of success by using Yahoo Japan, and searching with copy & paste Japanese characters, then viewing the results in English (e.g. 太陽堂光機㈱ for Taiyodo Optical Machinery (Co Ltd)).
3) I've been fortunate to find images of advertising material in Japanese. These can be run through an on-line "image text translator" such as Yandex. The translations are sometimes very odd, especially with older material, but switching the automatic translation from Japanese to Chinese (or vice versa) can often clear things up. Another option is to use a "text extractor", and copy the text into a "translator". Often a combination of approaches are required to form a picture of what an older advert might be saying. Japanese is a complex language for Westerners!
Sometimes a technical barrier prevents capture of worthy research. Obviously, if something is legitimately copyright protected, one has to respect that, but often it is more a case of technology getting in the way (e.g. slideshow image presentations preventing right-clicking). Here are a few methods to get around this obstacle (using Microsoft Edge).
1) "Web capture" (right-click option), and "prt sc" (keyboard option) both copy a screen image to the clipboard for pasting into an "image editor".
2) Here's a quick hack to copy images from Flickr when downloading has been disabled, and you don't want to bother with an image editor (*).
Right click on the image.
Select "Inspect" at the bottom of the pop-up menu.
This will bring-up an information pane, with <span class="facade-of-protect-zoom"></span> highlighted. The line of code immediately above provides the image address.
Mouse-over this address, and a pop-up window will provide a hyperlink to the image.
Follow that link, and right-click again for the "save image as" option.
3) "Online Image Extractors" can sometimes extract all the images linked to a web page at a click (I have no particular recommendation as to which one is best).
(*) I must say, I have no time for people who copyright documents they can claim no ownership of (e.g. camera instruction manuals, or magazine pages).