That's a nice one. So far I've acquired three pots by Masako Kunii.
Not so easy, but not too difficult. Here you are.
This is his
homepage. It's hardly up to date...
This one on
Yahoo.jap is a good place to check new pots, but I couldn't order anything using it. Just to check new products and see an item No.
And
Buyee is a place I search an item by the number and I can order from. They charge some small changes for buying an item for you and domesting shipping... like 300+500 yen. Very satisfied with their services. Keep you all safe these days.