[5] Before entering government service, Yabunaka was a senior researcher at the International Institute for Strategic Studies from 1990 to 1991.

[5] Yabunaka has represented Japan on a number of occasions and has negotiated trade deals with the United States, Australia and Indonesia.

[10] He handled Myanmar relations during the Kenji Nagai shooting incident, demanding an investigation and challenging governmental claims.

[11] Yabunaka replaced Toshiyuki Takano as Director General of Asian and Oceanian Affairs Bureau in 2002.

[12] In 2008 Yabunaka held talks with South Korean Ambassador Kwon Chul Hyun over disputed islets in the Sea of Japan.