After Japan's defeat in World War II, General Douglas MacArthur granted immunity to the country's Imperial Family.

On 10 March 1906, the Emperor Meiji granted Prince Yasuhiko the title Asaka-no-miya and authorization to begin a new branch of the imperial family.

On 6 May 1909, Prince Asaka married Nobuko, Princess Fumi (7 August 1891 – 3 November 1933), the eighth daughter of Emperor Meiji.

Upon returning to Japan that same year, The Prince and Princess began arranging for a new mansion to be built in the Art Deco style in Tokyo's Shirokanedai neighborhood.

[1] However, during the abortive February 26 Incident in 1936, Prince Asaka pressed the Emperor to appoint a new government that would be acceptable to the rebels, especially by replacing Prime Minister Keisuke Okada with Kōki Hirota.

The Prince's pro-Imperial Way Faction political sentiments, as well as his connections to other right-wing army cliques, caused a rift between himself and the Emperor.

While Prince Asaka's responsibility for the Nanjing Massacre remains a matter of debate, the sanction for the massacre and the crimes committed during the invasion of China might ultimately be found in the ratification, made on 5 August 1937 by Emperor Hirohito, of the proposition of the Japanese army to remove the constraints of international law on the treatment of Chinese prisoners.

[2][additional citation(s) needed] Supreme Commander of the Allied Powers (SCAP) officials interrogated Prince Asaka about his involvement in the Nanjing Massacre on 1 May 1946, but did not bring him before the International Military Tribunal for the Far East for prosecution.

Indeed, for politico-strategic and geopolitical reasons, General Douglas MacArthur decided to support the Imperial family and to grant immunity to all its members.