In 1941, he was made a member of the Imperial Privy Council; following Japan's defeat in World War II, Ikeda was banned from public political service.

While the Foreign Minister and others were opposed to any formal involvement with the Jewish people, on the basis of their uncontrollable nature and devious schemes as detailed in the Protocols of the Elders of Zion and the threat they posed according to Nazi ideology, Ikeda, along with Army Minister Itagaki, argued that a population of Jews would be a great asset to Japan, attracting foreign capital and improving world opinion towards Japan.

The meeting ultimately proved a crucial step in the development of the "Fugu Plan" which would bring several thousand Jews to the Empire of Japan, from Nazi-controlled Europe.

Ikeda became a member of the Privy Council in 1941, and was banned from engaging in political activity as a result, following the end of World War II.

[1] In December 1945, following the surrender of Japan, Ikeda was arrested on the orders of the US occupation authorities as a suspect on charges of Class A war crimes.

He withdrew to his summer home in Oiso, Kanagawa, but cooperated with the American occupation officials in the dissolution of the zaibatsu, which earned him the enmity of many former colleagues within the Mitsui group.