Who was called the "Gaijin Shōgun"?

The term shogun (将軍, lit. "army commander") is the abbreviation of the historical title "Seii Taishōgun." 征 (sei,せい) means "conquer" or "subjugate," and 夷 (i, い) means "barbarian" or "savage." 大 (dai, だい) means "great," 将 (shō, しょう) means "commander," and 軍 (gun, ぐん) means "army." Thus, a literal translation of Seii Taishōgun would be "Commander-in-Chief of the Expeditionary Force Against the Barbarians."

During the Edo period, effective power rested with the Tokugawa shogun, not the Emperor in Kyoto, even though the former ostensibly owed his position to the latter. The shogun controlled foreign policy, the military, and feudal patronage. The role of the Emperor was ceremonial, similar to the position of the Japanese monarchy after the Second World War.

Upon Japan's surrender after World War II, American Army General Douglas MacArthur became Japan's de facto ruler during the years of occupation. So great was his influence in Japan that he has been dubbed the Gaijin Shōgun.