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.
Head of state
The was drawn up under the Allied occupation that followed World War II and was intended to replace the previous militaristic and quasi-absolute monarchy system with a form of liberal democracy parliamentary system. The constitution explicitly vests all executive power in the Cabinet, who is chaired by the prime minister (articles 65 and 66) and responsible to the Diet (articles 67 and 69). The emperor is defined in the constitution as "the symbol of the State and of the unity of the people" (article 1), and is generally recognized throughout the world as the Japanese head of state. Although the emperor formally appoints the prime minister to office, article 6 of the constitution requires him to appoint the candidate "as designated by the Diet", without any right to decline appointment. He is a ceremonial figurehead with no independent discretionary powers related to the governance of Japan.