Japan is very much into gifts, if you have watched the 'Japan - how to #34 Gifts or #71' you would know.

And I think your japanese friend is just being polite, don't go to Japan with the idea of 'more'.

Perhaps you could bring some food that is famous in your own country, but not in Japan. But I would only do that if she and/or her parents are intrested in foreign food, I think you should know her enough to decide that on your own .

Have fun while your there!

EDIT: You can read the 'Etiquette when visiting Japan' topic on the Modern Japanese forum as well, it has some information about gifts too. I suggest you read it