Great Story!
There are not many hunters in Japan but from what I have learned, the duck hunting can actually be pretty good for the few people who go through the long process to purchase and shotgun and get a hunting license.
When I was in Japan visiting my wife family, we went on a trip along the NW coast, west of Tokyo. I saw lots of ducks on the rivers and marshes. Also, when in Hokkaido, I saw sea ducks along the rocky coast. Then I met an old duck hunter when we by chance stopped in his restaurant on a small island the way from Hiroshima to Shikoku. He had two beautiful drake Eura-Asian Wigeon mounted under glass and Golden Pheasant on the wall. He said the hunting there was good in the cold years.
Maybe some day my wife & I will move to her home country and I can be the only dot in Japan on the DHBP map!