The era based calendar in Japan is pretty confusing, the "normal" Gregorian calendar is used for almost everything now but some traditional official things still use it. There is a lot of traditional stuff there like your handwritten signature is somewhat unacceptable because you need a little stone stamp thing that's registered with the local government then used to sign documents (leases, bank stuff, government stuff). Maybe that has changed since I spent time there into the 90s. I needed one to lease an apartment.
The era calendar is also a "dog whistle" used by members of "nationalist" groups who don't like the post WWII democracy forced on them after surrender... Japan's "neo nazi" fringe.
Quite a few early Honda parts I have used over the decades (definitely seen into the 70s) have Showa dates stamped on them. I don't know when that changed or if some of their suppliers still use era dating.
There were many small suppliers for motorcycle parts, they didn't all come from big fancy factories. I came across a small shop - like really small, about what would be a two car garage here in a basically residential area of Osaka making Bowden cables (clutch, brake, throttle type) and packing them in Kawasaki labelled boxes... my friend with me (Japanese dude) spoke to them and they were not making fakes - these were factory parts - and they made them for other brands as well. They said they had another shop nearby making wiring harnesses.
(rant) Unrelated, why does the USA still use DMY or MDY dating rather than the YMD used by pretty much everywhere else in the world? (/rant)
