Moving back to the US? I found this in The Japan Times: some information on movers.
Allied Pickfords — phone (04) 5651-2747, fax (04) 5664-7134 or check out www.alliedpickfords.co.jp
Economove — call (toll-free) (0120) 981-862. Web site at www.economovejapan.com/index.htm
Econoship — phone (toll-free) (0120) 222-111, mail email@example.com or check online at www.econoship.net
Japan Express — call (toll-free) (0120) 228-322. Online at www.japanexpress.co.jp/hikkoshi/eng.htm
Japan Luggage Express Ltd — phone (toll-free) (0120) 48-0081 or check www.jluggage.com
Nippon Express — call (toll-free) (0120) 150-422 or find them online at www.nittsu.co.jp/english/e_index.htm
Premier Worldwide Movers — phone (03) 6402-2371. Web site at www.premierworldwide.com
Quoz — call (03) 5932-7777. Web site at www.quoz.biz
Shipmates — call toll-free on (0120) 225-188 or check www.yourshipmates.com
Shipping will generally take a week to 11 days, depending on the destination, and cost varies quite a bit depending on various factors such as where you are shipping to, what you are sending and so on.