Actually, red and gold is more associated with Chinese culture.
Japanese culture is red and white.
But gold is okay used in accents.
Red and White are auspicious colors.. for good luck in the Japanese culture.
Red and White are used traditionally for Japanese weddings.
You should also fold origami Cranes. 1,001 cranes for weddings.
These are always done, for important occasions.
In gold.
You can also serve Sake.
And Japanese tea.
Also do a "Banzai" toast at the banquet.
You can also have Japanese Flower arrangements. For center pieces.
Japanese flower arranging is called "Ikebana."
Or use Bamboo, to decorate.
http://www.japanesestylewedding.co.uk/ikebana_flower_deco...
Or Bonsai.
Or Japanese fans.
Or Japanese Chopsticks.
You could also use Japanese Umbrellas to decorate with.
http://shop.ebay.com/i.html?_nkw=japanese+wedding+accesso...
You should also have a "Daruma" doll. This is for all important occasions, in Japanese culture. As a gift to the couple.
All the best,
Susan