When speaking Japanese the Emperor of Japan is typically refered to as either Tennō Heika, meaning 'his majesty the heavenly sovereign', Tennō, meaning 'heavenly sovereign', or Kinjō Heika, meaning 'his current majesty'. It is considered disrespectful to use their given name.
Outside of Japan the Emperor is often known by his given name, ie 'Emperor...' followed by his given name.
The Emperor however has limited powers and so the Prime Minister of Japan could be descibed as the leader.
Taro Aso is the current Prime Minster (April 2009)
The ones who held real power in early japans society were the Military leaders
emporer
The title of Provincial leaders in Canada is 'Premier'
prime minister
President.
Prime Minister
Shah
Presidente or President.
"Pube Strummer."
Nara became Japans capital in 711 A.D., and lost the title as capital in 781 A.D.
The title is PRESIDENT.