In the Constitution of Japan, it is stipulated that "the Emperor shall be the symbol of the State and of the unity of the people." The current emperor (tenno), Akihito, is the 125th emperor, counting from Jinmu Tenno, who was the first to be enthroned in 660 B.C.. In this span, the role of the emperor was at times one of real power, and at times only the nominal sovereign. In the Meiji Constitution (the Constitution of the Empire of Japan) which was proclaimed in 1889, the emperor was made the chief of state with political and military power; but he lost that power with the Constitution of Japan which went into effect following the defeat in the World War II. From then until now, the emperor exists as a symbol without function in the administration of government, and only carries out affairs of state at national ceremonies.
The family headed by the Emperor is called koshitsu or kozoku. The imperial family has no surname but uses the appellation miya (meaning "prince," or "princess") granted by the Emperor. For example, the current Crown Prince is called Hironomiya Naruhito and he is commonly known overseas by the friendly name, Prince Hiro. After the Constitution of Japan went into effect, the laws of the country applied to the imperial family in the same way as to ordinary citizens, with the exceptions of the Family Registration Act, the right to vote or stand for election, and the right to adopt children. Although the imperial line is determined by a hereditary system whereby male heirs succeed to the throne, in a few cases, when the death of a reigning emperor left no heirs who could satisfy the requirements for imperial succession, the empress, imperial princess, or the crown princess acceded to the throne.
Click here for Japan's national holiday "Greenery day" This was the birthday of the Showa Emperor Hirohito who died in 1989.