Emperor Hirohito's surrender announcement reached Japan by radio on August 15, 1945.
The recorded address, formally called the Imperial Rescript on the Termination of the War, was broadcast at noon Japan Standard Time. It announced that Japan had accepted the terms of the Potsdam Declaration, although Hirohito used indirect, formal language rather than simply saying that Japan had surrendered.
The broadcast was historically significant because it was the first time many ordinary Japanese people had heard the emperor's voice. The recording had been made at the Imperial Palace on August 14 and was replayed the following day. Its classical Japanese wording and poor audio quality made the message difficult for many listeners to understand immediately.
August 15 is commonly observed as V-J Day in Japan and several Allied countries, although the formal surrender ceremony took place later. The distinction matters: the radio announcement communicated Japan's decision, while the signed instrument legally formalized the surrender on September 2.