The postal service in Japan is relatively inexpensive and very dependable. There are post offices all over the country, including many small towns and villages.
Within Japan, the cost for a standard size letter (up to 25g) is 84 Yen, and for a postcard, 63 Yen. The Japan Post English website is full of information on available services and prices.
Local Couriers
There are a number of commercial courier companies offering convenient and efficient services. These services can deliver suitcases to and from the airport, skis and snowboards to the ski lodge, and surfboards to Okinawa and beyond, at reasonable rates. There are also special services “cool-bin” for refrigerated and frozen goods.
International Couriers
Here are the main international companies. All of them offer services and websites in English.
Undeliverable Item Notice (Japan Post)