Looking for rolls of new Japanese coins

I live in Japan, near Tokyo.

Where can I buy rolls of new, uncirculated Japanese coins?

I have checked with banks in Tochigiken and in Gunmaken, who did not have any available, but they recommended NichiGin/Bank of Japan. The staff said that new Japanese coins are available only in boxed coin sets from the Japan Mint, not available anywhere in rolls of 50 new coins. But I have seen the rolls of 50 new coins, so I know they must be available somewhere in Japan. Thanks for any possible information.

Where did you see the rolls of 50 new coins you mention?

Pardon if it may have sounded like I saw them in person. So far, I have only seen rolls of new, uncirculated Japanese coins listed for sale on the internet, I have not yet seen them in person.