Interesting for sure. Hungary briefly had a different crown though:
(shitty iPhone picture I made)
On the topic of the japanese imperial regalia:
It isn’t exactly uncommon that a monarch had/has limited access to the regalia. In Europe from the Middle Ages onward until very recently monarchs usually had access to their regalia only during coronation. That’s why a lot of monarchs had so called House/“Private” Crowns - crowns to wear for representation. A good example for this is the Crown of Emperor Rudolf II.
