A head of state (元首, genshu), or chief of state refers to a person who has the power of external representation of a nation.
Japan
Japan does not have a clearly defined head of state in its constitution, which is often controversial, but the emperor is often treated externally as the ceremonial head of state.
Ancient Rome
A term used to refer to the highest authority in the early Roman Empire (ca. 27 B.C. - 3rd century B.C.). Princeps, Latin for "leader" or "first person".
The so-called "Roman emperor" was a position created by Octavian (Augustus), the founder, who gave himself prominent authority, but combined it with multiple offices as a moderate name that did not remind the Senate and the people of a despotic monarchy.
This led to the later term "principalities" (Principatus) for the political system that existed until the establishment of "despotism" (Dominatus) by the emperor Diocletian after the turmoil of the 3rd century.
