“No mention of the Japanese government finding this stuff elsewhere and planting it like it belonged their yet?
To me it is like finding more Dead Sea scrolls under the Belagio Las Vegas.”
It’s not that crazy. There was an amazing amount of commerce in the ancient world. The coins could have easily gotten there along trade routes. They may have been a curiosity held by Japanese who had never heard of the Roman empire.
Or maybe the Japanese were just holding them until they got a better exchange rate on the Forex.