What gift to bring when invited to a japanese home?

My friend and I are backpacking through Asia at the moment and are currently in Japan. My friends parents know a family in Yokohama. They met maybe 30 years ago, haven’t seen each other since but kept in contact (Sending a message on Christmas, etc).
Their parents excitedly let the family know, that we are in Japan.
This family now has invited us into their home for 3 nights.

Since at this point we have been away from our home country for months, we didn’t bring anything tipical for our region. Buying some food gifts from our country in a Japanese store feels a bit weird.

What should we bring as a gift? Are there any rules we sould follow?

by sitdownhamilton