You can be sure that North Korea either has or soon will have the new currency plates so they can wage a communist-style "war by other means" against Japan just as they have against the US by counterfeiting large quantities of high-quality US$100 bills over the years.
The Japanese-Malaya "banana money" is in uncirculated condition, so it has some but limited value, the others are in very good condition but none of them are from the late 1800s, so their value to collectors is probably low. Therefore, I've toyed with the idea of using one of the 100-yen notes at a convenience store just to see the reaction I'd get. Although the government accepts it as legal tender, shops do not have to and probably won't.
Yes, that's probably what happened to my silver dollars too. So that could have been you who swapped them out with cash, no?