In each of these positions, he played an important role under the economic plan of then prime minister Hayato Ikeda, which greatly helped Japan's postwar economy.

[1][4] He subsequently held other positions including President Of International University of Japan and as an advisor to the ministry of foreign affairs in 1982, and in 1989, as chairman of the Institute for Domestic and Policy Studies in Tokyo.

In 1986, Okita proposed a Japanese version of the Marshall Plan to support developing countries using Japan's internationally criticized trade surplus.

[1] Days prior to his death in 1993, he wrote a paper directed at the Clinton administration which pointed out that Asian countries were becoming less reliant on trade with the United States and more reliant upon trade with each other, expressing a hope that "the United States will support greater networking within Asia, and will cooperate with Asia as a whole rather than only with individual Asian countries."

He died of a heart attack while discussing US-Japan economic cooperation on a phone call with economist C. Fred Bergsten.