I was recently in Japan and a couple of my Airbnb hosts and a particular bookstore clerk were exceedingly kind and accommodating, even by the high standards of Japanese service. I left them the best review I could on Airbnb but I'm wondering if there's another way to thank them for such a service that has a more direct impact for them?
As an example of a direct impact, where I live, I would tip much more generously (even though I think tipping is a terrible system) but tipping isn't accepted in Japan.
What is a good way in Japan to thank or reward a small business for excellent service?