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.
Japanese absolute primogeniture debate
Some conservative lawmakers opposed Koizumi and said the debate was premature. The current emperor's cousin, Prince Tomohito of Mikasa, also opposed the proposal, saying that the official male members of the Japanese imperial family might take up concubines in order to produce male members because it was previously possible for a male illegitimate child to assume the imperial throne. Later he said that this remark was just a joke. Another solution would be to restore the Shinnoke (agnatic collateral branches of the imperial dynasty which had been disinherited by the United States) to the line of succession.