He was an advocate of military expansionism, counseling an alliance between Germany, Italy, and Japan to facilitate world domination.

On 23 May 1942, the Italian Foreign Minister Count Galeazzo Ciano wrote in his diary that Shiratori had said that the 'dominion of the world belongs to Japan, the Mikado is the only god on earth, and that both Hitler and Mussolini must become resigned to this reality.'

Shiratori was found guilty of conspiring to wage aggressive war by the International Military Tribunal for the Far East in November 1948 and sentenced to life imprisonment.

On 7 October 1978, Shiratori was one of fourteen Class-A war criminals controversially enshrined at Yasukuni Shrine.

[2] A memo from Emperor Shōwa, disclosed in 2006, revealed that he stopped visiting Yasukuni Shrine from 1978 until his death in 1989, because "they even enshrined Matsuoka and Shiratori.