The debate over Emperor Hirohito's accountability for government decisions and military operations up to the end of the World War II began before the end of the war and has continued even after his death. This book documents this controversy while providing insights into the Showa emperor's role in military planning in imperial Japan. It argues that Hirohito both knew of and participated in such planning and offers evidence that he was informed well in advance of the planned attack on Pearl Harbor. Using Japanese primary sources, this text aims to show that Hirohito's participation in the decision-making process was entirely consistent with his intellectual background and his passionate belief in the significance of the imperial tradition for the Japanese polity (kokutai) in prewar Japan.