Quick question here.
It seems like the fight 800 years ago took place in Europe.Yet the belt and the Greeeds speak Japanese.Also, the illustration of the king looked like a stereotypical European king.Explanation?
Most people worldwide are used to watching shows taking place in other countries but using their own language, thanks to dubs, so many series don't bother showing foreign characters talking in their own language.
The USA is one of the few places where live action dubs aren't acceptable by the mainstream public and so people talking in a "wrong" language might seem odd.
Well maybe I'm reading a bit too much into it, but a few hundred years ago when science was still being refined, a lot of research was done in different areas, resulting in a mix of cultures. A lot of terms in chemistry come from Arabic as they invented a lot of it. So maybe they used a fictional Japanese basis for the invention of the belt 800 years ago.