Emperor of Japan
Currently, the Emperor of Japan is the only head of state in the world with the English title of "Emperor". The Imperial House of Japan is the oldest continuing monarchical house in the world. The historical origins of the Emperors lie in the late Kofun period of the 3rd–7th centuries AD, but according to the traditional account of the "Kojiki" (finished 712) and "Nihon Shoki" (finished 720), Japan was founded in 660 BC by Emperor Jimmu, who was said to be a direct descendant of the sun-goddess Amaterasu. The current Emperor is Akihito. He acceded to the Chrysanthemum Throne upon the death of his father, Emperor Shōwa (Hirohito), in 1989. The Japanese government announced in December 2017 that Akihito will abdicate on 30 April 2019.
Prime Minister of Japan
The is the head of government and chief executive of Japan. The Prime Minister is appointed by the Emperor of Japan after being designated by the National Diet and must enjoy the confidence of the House of Representatives to remain in office. He is the chairman of the Cabinet and appoints and dismisses the other Ministers of State. The literal translation of the Japanese name for the office is "Minister for the Comprehensive Administration of ("or" the Presidency over) the Cabinet".