Having schlepped a ski parka unnecessarily through my last Asia trip, I'm very sympathetic -- you should have seen the looks I got carrying it through Manila aiport! But I agree with jlb, you're stuck with that stuff for the entire trip in that scheme.

If you are going to Japan first, why not ship it back to the U.S. from Japan? The post office system is extremely efficient in Japan, although not cheap. Mark it "returned U.S. goods" and I don't think you'll get charged duty at the U.S. end. There's a branch of the post office at NRT.

P.S. I actually did get to use my parka once on my trip -- waiting outside the international terminal at SFO for the car pickup service!