Japanese Butter

I am collecting butter for personal reasons. Namely butter from different countries, or different types of butter. I’m looking for Japanese butter, but most of the Asian grocery stores I’ve checked only have American butter brands if they even have any notable butter at all. I’ve checked Uwajimaya, H Mart, and T&T. I’ve heard good things about Hokkaido dairy and it would make a nice contrast to all my European butter. Any leads would be appreciated