舞鶴鎮守府
An opponent of Japan's decision to declare war on the United States, Takagi was removed from his position as Chief of the Research Section in 1942 and was reassigned as chief of staff of the Maizuru Naval District. Promoted to rear admiral on 1 May 1943, in September Takagi (due to his access and unique knowledge of classified files from his time as chief of the Research Section) was asked by Navy Minister Shigetarō Shimada to compile a report analyzing Japanese defeats during the Pacific campaign of 1942. Going far beyond its original purpose, Takagi's analysis of combat evidence, conditions in the Japanese home islands, and air and shipping losses as of that year convinced him that Japan's defeat was inevitable. Believing the only solution for Japan was the elimination of the Tojo-led government and negotiation of a truce with the United States, Takagi was hesitant to present the report to Shimada, instead beginning planning for the assassination of Prime Minister Hideki Tōjō before his removal from office in July 1944.