What is Golden Week exactly?
Showa Day (Shōwa no hi): The birthday of former Emperor Showa. Before 2007, April 29 was known as Greenery Day (now celebrated on May 4).
Constitution Day (kenpo kinenbi): A national holiday remembering the promulgation of the postwar constitution.
Greenery Day (midori no hi): Until 2006, Greenery Day was celebrated on April 29, the former Emperor Showa's birthday, due to the emperor's love for plants and nature. It is now celebrated on May 4 and is part of the Golden Week.
Children's Day (kodomo no hi): Also called boy's festival.
Sometimes by personal choice but mostly due to workplace scrutiny, Japanese are notoriously bad at taking personal leave. Instead, they only have two opportunities to take any extended time off: New Year's and Golden Week. However, New Year's is usually reserved for returning home for family, so Golden Week becomes the only time for leisure travel.
What does Golden Week mean for Foreign Travelers?
Crowds will swarm all popular attractions. Popular attractions like Disneyland and Universal Studios Japan will always have crowds, but they will be at max capacity during Golden Week.
Traffic outside of Tokyo will be atrocious. Although the streets of Tokyo will be relatively quiet after the mass exodus has occurred, the expressways and major thoroughfares outside of Tokyo will be jam-packed, especially at the beginning and end of Golden Week. This is important to note if you are planning bus travel anywhere through Japan during Golden Week.
Shinkansen and airports will be packed. Certainly, the busiest days will be at the beginning and end of Golden Week, but be aware that even during the week it may be difficult to secure seats on bullet trains or domestic flights unless you plan ahead.
Extended bookings at Hotels and Ryokan will be hard to find at popular travel destinations. You'll probably be okay to find places for one or two night stretches, but with the masses of people who will be traveling, finding extended bookings can be challenging.
Lots of mom and pop shops in major cities will be closed. Bigger businesses will capitalize on the Golden Week traffic, but since this is such an indispensable opportunity for leave from work, many mom and pop shops will take advantage of the exodus, especially in Tokyo. Just be aware in case there is a quirky shop or café that you're excited to visit--they may be traveling just like you!
How do you stay ahead of the Golden Week Wave?
Plan ahead. Take a look at your travel plans and note that the worst days to move around the country will be at the beginning and end of Golden Week. Book hotels, plane tickets, train tickets, etc. well in advance.
Look for accommodations through non-standard sources. If you are having difficulty finding traditional hotels or ryokan, look at AirBnB or other Minshuku (private B&B) options on the internet.
Reserve tickets for major theme parks in advance. Most theme parks in Japan offer options for reserving tickets online ahead of arriving at the park. If you can, do that, because they WILL sell out probably every day during Golden Week.
If all else fails, try travel agencies. Travel agencies are equipped to deal with Golden Week. If you are finding it difficult to get reservations for things you wanted to do, you may want to reach out to one of the domestic travel agencies like JTB. It will cost you, but it may be an option if you are trying to salvage an important part of your travel plans.
Golden Week can be immensely exciting and exceedingly frustrating depending on how you approach it. I hope these tips help you maximize your time if you happen to be traveling in Japan during this holiday period!