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 Go-Komatsu
He is officially considered to have been the Northern pretender from May 24, 1382 to October 21, 1392, when upon Emperor Go-Kameyama's abdication, Go-Komatsu is understood to have been a legitimate emperor (the 100th sovereign) from that date. In 1392, following the post"-Nanboku-chō" unification of the two formerly contending courts, the Southern Emperor Emperor Go-Kameyama reached an agreement with Go-Komatsu to alternate control of the throne between the Northern and Southern courts on a ten-year plan which effectively signaled the end of the southern court's claims to sovereignty. However, Go-Komatsu reneged, not only ruling for 20 years until his own abdication on October 5, 1412, but was succeeded by his own son, rather than by one from the former Southern Court. According to pre-Meiji scholars, Go-Komatsu's reign as a legitimate emperor spanned the years from 1392 through 1412. The present Japanese Imperial Family is descended from the Northern Court emperors.