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.
Emperor
Japanese monarchs were given their official title by the Chinese emperor. The new Japanese monarch after coming into power would send a representative to China and receive the anointment. They would receive their official title on several golden plates of several meters tall. Since the Japanese monarchs changed their title to 天皇 (Heavenly Emperor) in 607, the Chinese emperor refused to anoint the Japanese king, thus, ending relations with Japan for the next few hundred years. Although the Japanese emperors used Chinese imperial titles, rarely was the Chinese-style "Son of Heaven" used. In the Japanese language, the word "tennō" is restricted to Japan's own monarch; "kōtei" (皇帝) is used for foreign emperors. Historically, retired emperors often kept power over a child-emperor as de facto regent. For a long time, a "shōgun" (formally the imperial generalissimo, but made hereditary) or an imperial regent wielded actual political power. In fact, through much of Japanese history, the emperor has been little more than a figurehead.