[hinacamui]

Hey, I know that the OP has probably bought a gift and gave it already, but I'll leave a basic guide for giving gifts in Japan. Y'all can correct me if I'm wrong, this is just my opinion based on experiences while living in Japan.

I've found that practical things like soy sauce/spices etc. is popular. And the women are particularly pleased with that kind of thing. So maybe something like that, except with a foreign spin on it.
Soap works; but be careful with 'em and give something neutral and mild-scented. American, scented soaps/perfumes/etc. are really strong from a Japanese point of view.
Don't give objects/figurines. Japanese houses are usually small, and medium-sized/big "okimono" objects aren't the best gift unless you've seen the inside of the house already. Food is appreciated; good cheese is really expensive in Japan because everything is imported, nuts are expensive too (and good ones are rare). Ain't much good chocolates either. Maybe a Ghirardelli?
When buying presents overseas, keep in mind the packaging. If plastic and cardboard or paper are stuck together really securely, it might be really hard to throw away depending on how the city disposes of trash. Packaging that contains metal is a tad frowned upon, unless it's something reusable like an aluminum can.
Don't get anything too flashy or impressive, because they're going to feel obligated to give something of equal or better value.