The color pink
Japan is a very pink country. See that red and white? Mix it and you get pink!
But why is pink so symbolic in Japan? Well, let's start by talking about the word pink in Japanese. Momoiro is literally "the color of peaches". Nowadays, it's probably just easier to say the word Pink in English though.
This site talks about how pink is a symbolism of youth and freshness:
http://www.three-musketeers.net/mike/colors.html#pink
Sakura are also pink:
http://en.wikipedia.org/wiki/Cherry_blossom#Symbolism
As well as the flower Yamato Nadeshiko, the symbol of the ideal Japanese lady:
