Golden week (every April 29 to May 5), sometimes abbreviated GW, is not a holiday itself. Rather, it is several holidays that are always bunched together. This string of holidays, celebrated every April 29 to May 5, have created a very popular time for travel and is typically the longest holiday period of the year in Japan. Since the dates are fixed, Golden Week is better in some years depending on where the weekend occurs.
By the way, why is everyone hanging fish flags outside their homes? This is to commemorate Children’s Day in Japan (formerly it was known as Boy’s day and the hanging carp was a display of strength).
The national holidays which make up Golden Week:
April 29 – Showa Day
May 3 – Constitution Memorial Day
May 4 – Greenery Day
May 5 – Children’s Day