Ok!
man I wish I thought of doing that for a b-day party idea...
anyway here is probably what you need:
get some pocky, you can find some in walmart in the foreign foods isle.. It is a great treat
you can try these recipes.. although I have never tried them before.. so i can't tell you how they taste
http://www.epicurious.com/recipes/recipe_views/views/233720?mbid=gbaseyou can also do ramen or fish...
I would go with fruits and regular b-day food
only provide chopstick and see how many crazy foods you can eat only using chopsticks..
mix things up a bit just find things that look Japanese to you and put them as decorations(if you are going for cheep) you can make lanterns with popsicle sticks and wax paper and print out Japanese charms and hang them where ever.
Do karaoke! that is always a favorite ^-^ both in and out of Japan.
um.. for other games try going to
http://web-japan.org/nipponia/nipponia26/en/topic/index.htmlhere is instructions on how to make a paper crane
http://monkey.org/~aidan/origami/crane/I usually play go but that could be hard to get a hold of..
try playing video games
you can also just do normal sleep over games... scavenger hunt.. idk..
for music..
go to www.radioblogclub.com
if you become a member you can put together the music you want on there..(save to your favorites) they have lots of good Japanese and other music on there
I suggest Ayumi Hamasaki, Yoshida Brothers, Arashi, NewS, Yamashite Tomohise,w-inds, Utada Hikaru...hyde.. and whatever anime music you like..
try adding in a little of each of your guests interests ...
good luck
~ari4