The Empire of Japan (Kyūjitai: 大日本帝國; Shinjitai: 大日本帝国; Romaji: Dai Nippon Teikoku; literally Great Imperial State of Japan; officially Great Japan or Empire of Great Japan; commonly as Imperial Japan or the Japanese Empire) was an empire and world power that existed from the Meiji Restoration on 3 January 1868 to the enactment of the post-World War II Constitution of Japan on 3 May 1947.

Imperial Japan's rapid industrialization and militarization under the slogan Fukoku Kyōhei (富国強兵^?, "Enrich the Country, Strengthen the Army") led 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 ruled over a land area spanning 7,400,000 square kilometres (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 gained notoriety for its war crimes against the peoples of the countries it conquered. After suffering many defeats and the atomic bombings of Hiroshima and Nagasaki, however, the Empire of Japan surrendered to the Allies on 2 September 1945. A period of occupation by the Allies followed the surrender, and a new constitution was created with American involvement. The constitution came into force on 3 May 1947, officially dissolving the Empire. American occupation and reconstruction of the country continued well into the 1950s, eventually forming the current nation-state whose title is simply that ("the nation of Japan" Nippon-koku) or just "Japan" .

Japan ⁱ/dʒəˈpæn/ (Japanese: 日本 Nihon or Nippon; formally 日本国  Nippon-koku or Nihon-koku, literally the State of Japan) is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south. The characters that make up Japan's name mean "sun-origin", which is why Japan is sometimes referred to as the "Land of the Rising Sun".

Japan is an archipelago of 6,852 islands. The four largest islands are Honshū, Hokkaidō, Kyūshū and Shikoku, together accounting for ninety-seven percent of Japan's land area. Japan has the world's tenth-largest population, with over 127 million people. The Greater Tokyo Area, which includes the de facto capital city of Tokyo and several surrounding prefectures, is the largest metropolitan area in the world, with over 30 million residents.

Archaeological research indicates that people lived in Japan as early as the Upper Paleolithic period. The first written mention of Japan is in Chinese history texts from the 1st century AD. Influence from other nations followed by long periods of isolation has characterized Japan's history. In the late 19th and early 20th centuries, victory in the First Sino-Japanese War, the Russo-Japanese War and World War I allowed Japan to expand its empire during a period of increasing militarism. The Second Sino-Japanese War of 1937 expanded into part of World War II in 1941, which came to an end in 1945 following the atomic bombings of Hiroshima and Nagasaki. Since adopting its revised constitution in 1947, Japan has maintained a unitary constitutional monarchy with an emperor and an elected parliament called the Diet.

The Emperor of Japan is "the symbol of the state and of the unity of the people" according to the 1947 Constitution of Japan, which dissolved the Empire of Japan when it was adopted by the Postwar Japanese government. He is a ceremonial figurehead under a form of constitutional monarchy and is head of the Japanese Imperial Family with functions as head of state. He is also the highest authority of the Shinto religion as he and his family are said to be direct descendants of Amaterasu.

The Emperor is called the Tennō (天皇) in Japanese, literally meaning "heavenly sovereign". He is also referred to in English as the Mikado (帝) of Japan. Currently the Emperor of Japan is the only remaining monarch in the world reigning under the title of emperor.

The Imperial House of Japan is the oldest continuing hereditary monarchy in the world. In Nihon Shoki, a book of Japanese history finished in the eighth century, it is said that the Empire of Japan was founded in 660 BC by Emperor Jimmu. The current emperor is His Imperial Majesty the Emperor Akihito, who has been on the Chrysanthemum Throne since his father the Showa Emperor (Hirohito) died in 1989.