At the beginning of World War II in 1942, the building was converted to a Red Cross casualty station. When Singapore fell to the Japanese, it was used to house the Japanese Broadcasting Department, the Military Propaganda Department, the Military Information Bureau and the broadcast department of the Indian National Army's Provisional government of Free India during the occupation period. On 21 October 1943, Subhas Chandra Bose announced the formation of the Provisional Government of Azad Hind (Free India) at Cathay Building with himself as the Head of State, Prime Minister and Minister of War. The Japanese utilised the building to broadcast propaganda in the Japanese language. It was also the residence of film director Yasujirō Ozu from 1944 till the end of the war.