It seems unlikely to me that the Third Reich would have just let those claims go. Was there ever a dialogue between the Axis powers regarding their fate, and/or any secret plans on Germany's part to eventually reclaim them? If the latter case is true, did Japan ever suspect that such plans existed, and did they do anything to prepare for that eventuality?
Interesting question.
In the Tripartite Pact of 1940 Germany and Italy agreed to give Japan a totally free hand in Asia and the Pacific: "ARTICLE 2. Germany and Italy recognize and respect the leadership of Japan in the establishment of a new order in Greater East Asia."
It seems the Nazis were too busy conquering, colonising and exterminating hundreds of millions of people in Europe be terribly interested in Qingdao and a few scattered islands in the Pacific, which had never been terribly important in the first place. https://books.google.com/books?id=wSMzDAAAQBAJ&pg=PT42#v=onepage&q&f=false