駐日アメリカ合衆国大使
Yabunaka has represented Japan on a number of occasions, and has negotiated trade deals with the United States, Australia, and Indonesia. He has had contact with a number of United States diplomats, including hosting current United States Ambassador to Japan John Roos shortly following Roos' appointment. During the first, second, and third rounds of the Six-party talks, Yabunaka represented Japan as chief delegate. The Japanese government also sent Yabanuka as a delegate to China to discuss issues of natural gas reserves under the East China Sea.