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.
Pretender
Since 1911, the Japanese government has declared the southern claimants were actually the rightful emperors despite the fact that all subsequent emperors including the then-Emperor Meiji were descended from the Northern Court, reasoning the Southern Court retained possession of the Three Sacred Treasures, thus converting the emperors of the former Northern court into mere pretenders. In other words, six former emperors of the Northern Court have been counted as pretenders instead since then. As a result of this compromise, the present Japanese Imperial Family is descended of the Northern Court Emperors.