After we returned from Japan the big sister decided to have a Japanese birthday party- all on her own- I promise there was no prompting on my side! took the legs off a craft table and put it on some packing boxes covered in fabric to make our floor table. We had the place mats, soba plates and cushions already- but you could always get creative and use what you have.
We found some sushi candles and used those for the cake, which we made ourselves in the shape of a sushi plate. Now if only I knew how to spell birthday....
Japanese rubber stamps on plain fans made for a simple craft.