Kirk here. Even though I’ve lived in Kumamoto and have been writing about all things Kumamoto for a while (today, Oct 17, is our 25th anniversary), I’ve never thought about a connection between Miyamoto Musashi and world-class fishing equipment. Well, according to this article, one exists:
Swords, Samurai, and the Art of Making World Class Fly Rods https://www.yardbarker.com/general_sports/articles/swords_samurai_and_the_art_of_making_world_class_fly_rods/s1_17329_40891002
In a nutshell, the idea is that craftsmanship that goes into G. Loomis fishing rods made at the Shimano factory in Kumamoto is rooted in the samurai spirit of which Miyamoto Musashi is emblematic. Somehow, Joe Rogan gets brought into the discussion because he is so enamored of Musashi that he has him tattooed on his arm. (Sorry Joe, your homage to Japanese culture will cause you to be excluded from quite a few onsen here. :( )
In regard to the Kumamoto Factory, I could confirm that there is a Shimano factory in Yamaga and that Shimano owns G. Loomis but I don’t know much more than that.