He is. The Japanese Emperor Naruhito is the only man with the title Emperor in the world. No other country still has a similar titled ruler or figurehead — he’s the “last man standing”. The Kaiser is long dead, the Tsar is, too. Naruhito stands alone, the sole head of a family tree that first entered recorded human history 2600 years ago.
So the ancestors of Naruhito, 64, were already ruling Japan 600 years before the birth of Christ. And the bloodline is fragile. The family tree small. Only the direct male line matters — any female member of the family has to leave the royal family and the line of succession upon marriage. Only the sons of sons can apply. Naruhito, for the record, has no sons, only a daughter. His brother only has one son. His nephew, therefore, is the only heir to the throne.
Should Naruhito’s nephew only father daughters, like Naruhito himself and some of his uncles, the Japanese imperial bloodline in direct male line will die out. There is only one Emperor in the world — and only one heir to his throne. A legacy of 2600 years never before looked so fragile.