It is not actually a week, but it refers to the series of holidays from the end of April to the beginning of May in Japan. The actual holidays making up the Golden Week are April 29th (Showa Day), May 3rd (Constitution Day), 4th (Greenery Day), and 5th (Children's Day).
April 29th (Showa Day)
It is the birthday of Showa Emperor, who died in 1989, and is now the day to honor him.
May 3rd (Constitution Day)
It is the day in 1947, the new postwar constitution was put into effect.
May 4th (Greenery Day)
It is the day to pay respect to the environment and nature.
May 5th (Children's Day)
It was used to be called Boy's Day or Boy's Festival. Many families fly Koinobori Carp Streamers and display miniature sets of samurai armor or dolls, both symbolizing strength, power, and success in life. The Girl's Festival is celebrated on March 3rd.
A few days do not result in a whole week of consecutive holidays, but many people use their paid holidays to get the entire time off from April 29th through May 5th, and in some cases, there's even a compensation holiday on either April 30th or May 6th if any of the previously mentioned holidays falls on a Sunday.
Golden Week 2019
In 2019, the Emperor is scheduled to abdicate on April 30th, followed by the ascension to the throne of the new Emperor on May 1st which will be made a national holiday. As a result, April 30 and May 2 will also become national holidays (because according to law, a day between two holidays also becomes a holiday), creating an unprecedented, consecutive 10-day holiday from April 27th to May 6th.
At this time of the year in Japan, the weather is very pleasant and the temperature is neither too cold nor too hot. Because of that, it is the peak season for the Japanese to travel despite the fare being much more expensive than the off-season.
First Tea Harvest
It is also the time of year when green tea harvesting begins. The new tea leaves are picked from around mid-April to around mid-May. Once picked, the new leaves head off to be steamed and dried. This process stops the oxidation and preserves all the beneficial qualities we’ve grown to love in green tea.
There is an event that pays tribute to the old tradition Ochatsubo Dochu Gyoretsu, a procession of large ceramic jars containing freshly picked tea leaves. From the time of the samurai the tea would be sent from Uji to Edo (Tokyo) and many other domains across Japan.