We do have some freshwater pearls available in Japan. But more than 99% of them are imported from China. I would never suggest buying freshwater pearls from here because the price is much better there.
We had a lake that produced good quality freshwater pearls for a long time. Lake Biwa became so polluted, however, that all the farms have closed.

There is a new lake, however, that is producing pearls. It is called Kasumigaura. These pearls are typically large, and quite round. Most of them are pink. They are nice pearls, but very, very expensive.