Now we're doing the "trawling through tenuous evidence thing to find answers for questions no one's actually interested in" thing for Yamaha, too!
One of the barriers to a full history is the Japanese language. For example, Enya made model aircraft engines from I think the late 1940's on. In the 1960's, Model Rectifier Corp. (MRC) had exclusive rights to import these into US for the western world. However, there were a series of engines that were not part of this export. They were available in the Orient (Japan, Korea, Taiwan, Malaysia, Singapore and I think possibly Australia and New Zealand.) These were their line of smaller A and Half-A engines of .049 to .08 cubic inch displacement.
A member of the Cox Engine Forum would travel to Japan on behalf of his employer several times a year. Over the years he bought these oddities, would discuss them in the forum. None of the US hobby stores sold them. They are good engines. I guess that the powers to be felt that these would not compete well with Cox, who made engines in half-A and A sizes. Instructions and literature were in Japanese, not English.
Back to your point. Rather than trawling, someone who has lived or traveled regularly to Japan connected with the music industry, who knows the language would be the best person to pipe in. There are things made abroad that never make it to western shores, for one reason or another.
What's next, the history of Antigua Winds models?
This I would be interested in as it has been a mystery to me, would make a good separate thread. I have two of their instruments, an older alto sax and an newer low-A bari. Both play extremely well, like professional models. The alto is on par with my old Yamaha YAS-61. I suspect the possibility of KHS roots but information is obscure. The brand seemed to slowly evaporate after 2014 with the debutting of the Allora brand. I don't know if they were by the same manufacturer.
Also, the Venus brand is a bit of a mystery. I always thought they were made in China, both, my sop and tenor have no country of origin on them. Recently it was suggested they came from Taiwan. The brand seemed to fade away about the same time Antigua Winds faded away. Are they related? I don't know. However, they also play extremely well for budget saxes, like an intermediate. Stephen Howard's write up on the Venus alto is positive.