Kokutai is a uniquely Japanese concept often translated as ‘national polity’ or ‘national essence.’ 

It refers to the unique constitutional and spiritual essence of the Japanese nation and its people, centered historically on the Emperor as a symbol of continuity and unity. Kokutai is not just a political constitution but a broader idea of Japan’s national identity and political order. It embodies ideas about the Emperor’s divine descent (from Amaterasu, the sun goddess), Japan’s unique historical destiny, and the special relationship between the ruler and subjects.

In prewar and wartime Japan, Kokutai was used to legitimize the Emperor’s absolute sovereignty and Japan’s political system. It was often invoked to promote national unity, loyalty, and resistance to foreign political ideas like liberal democracy or socialism. Kokutai placed the Emperor at the center of sovereignty and moral authority. This made Kokutai both a political doctrine and a national ideology that justified Japan’s imperial system and mobilized the population. 

Emperor Hirohito ascended the throne in 1926; the period of Japanese expansion in East Asia began before and accelerated after his accession, but the direct role of the Emperor in authorizing specific expansionist plans is debated by historians. Herbert P. Bix (Hirohito and the Making of Modern Japan, 2000) argues Hirohito was actively involved and gave imperial sanction to expansionist policies, though sometimes reluctantly. Akira Fujiwara and other scholars suggest Hirohito was more a constitutional monarch fulfilling formal roles with limited initiative.

The notion of “Greater East Asia Co-Prosperity Sphere” was promoted from the late 1930s, becoming a public and official vision for Japanese dominance in East Asia and the Pacific. Emperor Hirohito actively endorsed this vision in state occasions and speeches (e.g., the Imperial Rescript on the National Spiritual Mobilization in 1937). Planning was largely by military and government leaders.

The Rescript was the formal proclamation issued by Emperor Hirohito to rally the Japanese people’s spirit and unity in support of the nation’s war efforts following the outbreak of the Second Sino-Japanese War. The rescript was intended to strengthen national morale, urging loyalty, sacrifice, and collective effort to support the military and government. It framed Japan’s war as a sacred duty, emphasizing traditional values like loyalty to the Emperor, filial piety, and social harmony. It served as a foundation for wartime propaganda and education, promoting nationalism and support for militarism. It was significant in that it marked a formalization of the Japanese government’s efforts to link traditional imperial ideology (kokutai) with modern total war mobilization.

During the war, Hirohito gave formal assent to military operations and policies in Imperial Conferences, including the declaration of war on the United States and the expansionist campaigns in Southeast Asia and the Pacific (1941 onward). Imperial Conference minutes show Hirohito’s involvement in high-level decisions, though historians differ on whether this reflects active strategic direction or constitutional approval (as noted above)

Understanding kokutai is crucial to grasping why Japanese leaders in WWII were so concerned about preserving the Emperor’s status during surrender — they feared that losing kokutai meant losing Japan’s national identity itself. It also explains the intensity of nationalist and militarist resistance in 1945, when unconditional surrender seemed to threaten kokutai.

Americans do not have anything like Kokutai at least in personification..  Presidents come and go – the Constitution is our anchor of continuity and unity. It embodies who we are as Americans but does not establish a special relationship with a particular president or their descendants – and certainly we do not ascribe divine status to the president.

In the early war period (1941–43) kokutai was not widely understood in detail by U.S. policymakers. Early wartime rhetoric tended to focus on Japan as a militarist aggressor without deeply engaging with its unique political culture. However, intelligence reports, embassy cables, and academic analyses increasingly informed US officials about Japan’s unique emperor-centered political ideology.

By the 1944-1945 period as the Allies prepared the Potsdam Declaration (July 1945) demanding “unconditional surrender,” American leaders realized that insisting on unconditional surrender might threaten the Emperor’s status—a core part of kokutai. Leaders like Secretary of State James F. Byrnes and members of the Joint Chiefs were briefed on the significance of the Emperor and kokutai to Japanese society and governance.

By the final year of WWII, American political leaders had developed a practical understanding of kokutai’s centrality to Japan’s political order and cultural identity. Did practical understanding affect war policy or execution? The Potsdam Declaration (demanding unconditional surrender) would give no evidence of such. From post-war interviews, review of captured documents, and other sources, there is little to no indication of Allied awareness – either way.

Remember that this series is taking a path that assumes atomic bombs were not available as a means of exploring how the war would end and at what cost. That being said, if one looks at the historical record of the events immediately after the 2nd atomic bomb struck Nagasaki, the fate of kokutai and the Emperor was the principal concern as the Supreme War Council tried to reach a unanimous decision to recommend to the Emperor. But that is a story for a later post.

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Image credit: various photographs from Naval Aviation Museum, National World War II Museum, and US Navy Archives.