Tatsuji Takeuchi 
War and Diplomacy in the Japanese Empire [PDF ebook] 

The author had access to many Japanese texts and private documents dealing with undercurrents of diplomacy and with constitutional history; he also had the advantage of knowing the Japanese attitude towards life and politics, the terrific force of Japan’s traditions as they are brought to bear on international relations, while at the same time possessing the necessary perspective provided by occidental training in analysis and criticism. The result is a revealing and careful exposition of the structure and psychology of the Japanese government, from the Emperor down, and the only history of Japanese diplomacy as a cause of war that has ever been written.