Japan assesses a consumption tax on items. As a tourist, you can be exempted from paying this tax if the item purchased is destined to be used outside of Japan. You will need to present your passport when making the purchase at designated “tax free” shops. The clerk will provide the appropriate paperwork for the customs officer. Only items purchased at tax free shops are exempted from the consumption tax.
Swords, guns, and certain computers require additional export licenses if they are being sent out of Japan.