Well , sure looks like the tile is 100% Japanese manufacture .... the printing/overglaze ... not a clue here .
It's a small bummer that your trivet has gotten cracked along the way ... lots of these got dropped/dropped on & had the same fate as yours , cncurtis .... curious to know the size of the tile (metric or not) , too .
I'm not the ultimate authority on items of this vintage , but it looks like alot of like items that were on the U.S. market (new) in the 1970's-1980's to my old eyes .
Perhaps it would like a nice waxing , though (the iron , that is) !