[1] After the bombings of Hiroshima and Nagasaki, the Japanese side prepared the notification of surrender to allied forces through protecting power Switzerland, and the Showa Emperor announced the declaration of the end of the war on August 15.
Over the next two years, Japan and U.S. General Douglas MacArthur cooperated in drafting the new constitution, which was ratified by the House of Representatives on August 24, 1946, by the House of Peers on October 6, and by the Privy Council on October 29, then promulgated by the Emperor on November 3, 1946, the Emperor Meiji's birthday, and came into effect on May 3, 1947.
[2][3] Initially, Prime Minister Shigeru Yoshida wanted to observe Constitution Memorial Day on November 3 because it was already a holiday; furthermore, the date of the signing also coincided with the start of trials by the International Military Tribunal for the Far East.
[citation needed] Constitution Memorial Day is a time to reminisce about the events of Japan's history.
In 2019 a one-off Platinum Week was held, with extra events and a longer duration, to commemorate the inauguration of the new emperor, Naruhito.