Records of heads of state
Officially, the current Emperor of Japan, Akihito is the 125th in line from the first emperor Jimmu, who is variously believed to have reigned in the 1st or 7th century BC. The earliest documentary evidence is only for the 29th emperor, Kinmei (AD 509–571); however, this is sufficient such that even the most conservative of estimates still places the Japanese imperial family as among the oldest lines in the world today.
Kumazawa Hiromichi
In 1946-1947, Hiromichi was only the first of roughly nineteen men who put themselves forward as Japan's rightful Emperor. As a direct descendant of the Southern Court emperors of the Nanboku-chō period, he argued that Emperor Hirohito was illegitimate. He pointed out that Hirohito's entire line is descended from the Northern Court emperors. He produced a koseki detailing his bloodline back to Emperor Go-Daigo in Yoshino, but his claims and rhetoric failed to inspire anything other than sympathy.