The Empire of Japan, officially the Empire of Great Japan or simply Great Japan (Dai Nippon), is an empire and world power that exists from the Meiji Restoration on January 3, 1868 to the enactment of the post-World War II Constitution of Japan on May 3, 1947.

Imperial Japan's rapid industrialization and militarization under the slogan Fukoku Kyōhei ("Enrich the Country, Strengthen the Army") leads to its emergence as a world power, eventually culminating in its membership in the Axis alliance and the conquest of a large part of the Asia-Pacific region.

At the height of its power in 1942, the Japanese Empire rules over a land area spanning 7,400,000 square kilometers (2,857,000 sq mi), making it one of the largest maritime empires in history.

After several large-scale military successes during the Second Sino-Japanese War (1937–1945) and the Pacific War, the Empire of Japan also gains notoriety for its war crimes against the peoples of the countries it conquers.

After suffering many defeats and the atomic bombings of Hiroshima and Nagasaki, however, the Empire of Japan surrenders to the Allies on September 2, 1945.

A period of occupation by the Allies followed the surrender, and a new constitution is created with American involvement.

The constitution comes into force on May 2, 1947, officially dissolving the Empire.

American occupation and reconstruction of the country continues well into the 1950s, eventually forming the current nation-state whose title is simply that ("the nation of Japan" Nippon-koku) or just "Japan".The Emperors during this time, which span the entire Meiji and Taishō, and the lesser part of the Shōwa eras, are now known in Japan by their posthumous names, which coincide with those era names: Emperor Meiji (Mutsuhito), Emperor Taishō (Yoshihito), and Emperor Shōwa (Hirohito).