Showa Day commemorates the reign of Emperor Hirohito who reigned from 1926 to 1989. After wondering why there would be a national holiday recognizing Emperor Showa (as he is commonly referred to in Japan) because of his turbulent reign, I read up on his history here. Very interesting.
Constitution Memorial Day celebrates the time during which Japan developed their now current democracy shortly after WWII. This was a very big deal as it dissolved the previous absolute monarchy of the emperor. So the emperor during that time (Emperor Showa/Hirohito) stepped down from his position of absolute authority to essentially being a figure head.
Greenery Day has a very interesting history. It reminds me a bit of Earth Day in the USA. Emperor Showa was very interested in biology-especially marine biology-and himself a big supporter of environment and so-called "green" issues.
Children's Day is the most visibly celebrated, as far as I could tell. People celebrate and pray for the success and health of their children, boys in particular. They fly special wind sock flags in the shape of carp, which symbolizes strength and success. Girl's have their own special holiday (alas-it is not a day off) every March 3rd. It is called Hina Matsuri.
Golden Week is, for obvious reasons, a popular time for people to vacation. We were originally scheduled to go to Hong Kong for ten days, but alas...the earthquake struck and our plans were changed. But all turned out well. We have been having a splendid Golden Week complete with adventures in Tokyo and fields full of flowers.
More to come...