In 1940, he assumed the post of the general affairs department of the Taisei Yokusankai (大政翼賛会, "Imperial Rule Assistance Association") which was Japan's para-fascist organization created by Prime Minister Fumimaro Konoe on October 12, 1940, to promote the goals of his Shintaisei movement.

During World War II, he changed his opinions and left the Taisei Yokusankai and strongly opposed the policy of the Hideki Tojo cabinet.

In 1966, he established a cultural exchange system Nihon Taigai Bunka Kyokai at the request of Soviet Russia, and assumed the post of its president.

At that time, Matsumae was the top of the engineering bureau of the Tsushin-in (Ministry of Communications), and the draft came in a telegram on July 18, 1944.

Matsumae found the blackened body of the Director, Tadasi Yoshida, who had helped him with the development of non-loaded cable.

[citation needed] Squatting by his side was his wife, apparently drained of blood (5 days later she died of radiation sickness).

[citation needed] Matsumae and technicians of his team were continuously being bathed in radiation and had no idea when their bodies would start to undergo some change.

While serving as an engineer in Tokyo, he attended Bible classes by Uchimura Kanzō, the founder of the Nonchurch Movement (Mukyōkai) of Christianity in the Meiji and Taishō period Japan.

[5][6] Matsumae was interested further in education, leading to the establishment of many schools later, and the European center of Tokai University in Copenhagen, in 1970.