Today is the Emperor's Birthday which is a national holiday in Japan. In Japan, based on the ancient Chinese imperial era system, an era name ("gengo") is assigned to each emperor's ruling period. Japanese people use the imperial era name combined with the years counted from the first year of the period, as well as the Christian era system. Government offices usually use the imperial era system, so we are constantly required to translate from one system to the other.
The Gengo of the present emperor Akihito is "Heisei" and this is the year "Heisei 22." Today, Emperor Akihito turned 77; therefore it is at the age of 56 that he started his rule when his father Emperor Hirohito passed away in January 1989.
Although today, after the WWII, the Emperor has become a mere figurehead politically, a number of people come together at the Imperial Palace to celebrate his birthday.