A Tennō (天皇, initially Mikado (帝) when used in English), also known as the Emperor of Japan, is the emperor or monarch of the country of Japan, as well as the only title for Emperor that is still in use during the common era. Unlike most Western instances of the title Emperor, the Emperor of Japan rarely acted as the supreme battlefield commander since the establishment of the shogunate in 1192, and were usually controlled by external forces such as the shoguns or their shikken agents during the Kamakura era (1203-1333 AD). In fact, the title never actually became the embodiment of all sovereign power until the Meiji Restoration in 1867. The title was eventually reduced to a figurehead status when drafting the new constitution in 1947, as a result of World War II.
The word means "heavenly sovereign."
Although not a formal title for the Japanese Emperor, a similar term, used for archaic Japanese, was Kōtei, which was itself derived from a legendary figure from Chinese history known as the Yellow Emperor.