Always somewhat of a rebel, Prince Higashikuni's behavior in Paris scandalized the Imperial Court. He had a French mistress, enjoyed fast cars and high living. He left his wife and children in Japan, and the death of his second son did not prompt his return. In 1926, the Imperial Household Ministry dispatched a chamberlain to Paris to collect him. Upon his return to Japan, he was assigned to the Imperial Japanese Army General Staff Headquarters. Promoted to major-general in August 1930 and appointed commander of the 5th Infantry Brigade (1930–1934), he was promoted to lieutenant-general in August 1934 and given command of the IJA 4th Division (1934–1937). After the start of the Second Sino-Japanese War, he headed the Imperial Japanese Army Air Service (1937–1938), and the IJA 2nd Army stationed in China from 1938–1939. He was promoted to general in August 1939. According to a memo discovered by historian Yoshiaki Yoshimi, Prince Higashikuni authorized the use of poison gas against the Chinese on 16 August 1938. On 13 May 1939 the Imperial General Headquarters authorized the use of poison gas to Japanese Northern China Area Army（大陸指第四百五十二号). Only riot control agents were used till then. Prince Higashikuni moved to the post at home dated 4 January 1939. Promoted to full general, The prince was awarded the Order of the Golden Kite, 1st Class in 1940. Before Japan entered the Second World War, on 15 October 1941, outgoing Prime Minister Fumimaro Konoe proposed Prince Higashikuni to Emperor Hirohito as his successor for prime minister. Konoe believed that only a member of the Imperial Family with a distinguished military background could restrain the pro-war faction led by Generals Hajime Sugiyama, Hideki Tōjō, and Akira Mutō. Prince Higashikuni was also the choice of both Chief of Staffs of the Army and the Navy. However, both Emperor Hirohito and the Lord Privy Seal, Kido Kōichi, believed that it would be inappropriate for a member of the Imperial Family to serve in that position, as he could be blamed for anything which went wrong in the war. Thus, two days later, Hirohito chose General Hideki Tōjō as Prime Minister. In 1946, he explained this decision: "I actually thought Prince Higashikuni suitable as Chief of Staff of the Army; but I think the appointment of a member of the Imperial house to a political office must be considered very carefully.