Cheap way to send my stuff to Japan?

I'm moving back to Japan in less than 3 weeks and I always have trouble managing my things when moving between US and Japan. Shipping stuff isn't as expensive from Japan to the US compared to vise-versa. When moving from US to Japan in the past, I've always just swallowed an extra 200USD taking a third luggage with me. But that is such a pain in the butt! Any advice??? Shipping anything from the US lately will literally cost a kidney, and I want to ship a big box.

Thanks

by BerryTella1