Getting back to his homeland, Shimoi helped the Italian Embassy in Tokyo to stop the pro-Ethiopian activities of the Japanese rightist clubs during the war in Ethiopia. Shimoi was one of the best known Japanese supporters of Italian fascism, seeing some analogies between the fascist principles and the traditional values of Japanese culture, especially the Bushido. He argued that fascism was a natural ramification of the risorgimento, and that its role was to be a "spiritual movement" that would make Italians identify as being part of the new nation. While being a supporter of fascism in Italy, Shimoi didn't ever promote it in Japan, considering such movement an Italian cultural phenomenon.