The Emperor of Japan is, according to the 1947 Constitution of Japan adopted by the Postwar Japanese government, "the symbol of the state and of the unity of the people," which simultaneously dissolved the Empire of Japan. 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. In his dual role as head of a religion and head of state the Emperor resembles the British monarch, who is "supreme governor" of the Church of England.
The Emperor is called the Tenno (天皇) in Japanese, literally meaning "heavenly sovereign". He is also referred to in English as the Mikado (帝) of Japan.
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.
The role of the Emperor of Japan has historically alternated between a largely ceremonial and symbolic role and that of an actual imperial ruler. Since the establishment of the first shogunate in 1192, the emperors of Japan have rarely taken on a role as supreme battlefield commander, unlike many Western monarchs. Japanese emperors have nearly always been controlled by external political forces, to varying degrees. In fact, from 1192 to 1867, the shoguns, or their shikken regents in Kamakura (1203–1333), were the de facto rulers of Japan, although they were nominally appointed by the emperor.
Since the mid-nineteenth century, the Imperial Palace has been called "Kyujo" (宮城), then Kokyo (皇居), and located on the former site of Edo Castle in the heart of Tokyo. Earlier emperors resided in Kyoto for nearly eleven centuries.
The Emperor's Birthday (currently celebrated on 23 December) is a national holiday.