You can still smoke in public
This summer we saw far less people smoking in Japan (Tokyo, Osaka and Kyoto) than we do in the UK.
Like with drinking and eating, smoking didn't appear to be acceptable whilst walking around in this cities. There were some smoking shelter areas where you found people stood both in the streets, in theme parks, outside of parks/shrines and inside public buildings such as the airport. No smoking at all seen inside buildings, or even in the streets outside those specific smoking areas.