St. Regis Osaka has a very nice beer garden on its 12th floor outdoor terrace overlooking a Japanese rock garden. As it does not appear to be advertised yet for this year, here's a link to their 2019 summer beer garden menus with varied options.
https://suposaka.net/%E3%80%90st-reg...-april-26-fri/
I was there a few years ago and really enjoyed it with free-flowing beer, wine, Mumm Grand Cordon champagne, cocktail options along with food. My review can be read here:
https://www.flyertalk.com/hotel-revi...ka-review-3335
St. Regis Osaka outdoor beer garden
St. Regis Osaka outdoor rock garden