As you mentioned, tipping isn’t accepted in Japan. As to the situation, all you can do is leave them the best review you can.

[Airbnb][1] provides some guidance on this:

> #Should I tip my experience host?

> It's up to you. Your host set a price they expect will fully cover your experience. We suggest you research cultural hospitality norms in your destination. If you want to show appreciation for your host, write a review encouraging other guests to book their trip.


  [1]: https://www.airbnb.com/help/article/1590/should-i-tip-my-experience-host