Some stores permit foreign customers the buy clothes tax free. The stores which provide tax exemptions are major department stores and stores that have the words TAX FREE written on the storefront. Many small shops do not allow tax free sales, so it is a good idea to ask if products are tax free. Also, you should be aware that even at major department stores, food products are not eligible for tax exemption. The eligible price is a total purchase of 10,001 yen and up. If you buy one item worth 5001 yen and one worth 5000 yen, the total is at least 10,001 yen, so it is eligible for tax exemption. The tax exemption amount is the consumption tax amount, which is 5%. There are 2 tax exemption methods: (1) deducting 5% at the time of purchase (for each one product equaling 10,001 or higher) and (2) after purchasing, take all the receipts to the tax exemption counter, complete the exemption procedure, receive the taxed portion in cash, and use the receipt as the tax exempt amount. Most department stores use method (2). Whichever method you use, a passport is required, so make sure to have it with you.
The 5% consumption tax imposed is not refundable for purchases of consumable items such as food and beverages. At many department stores like Isetan, Seibu and Matsuzakaya, you typically pay the full cost at the cashier and go to a tax refund (税金還付 zeikin kanpu or 税金戻し zeikin modoshi) counter, usually located at one of the higher floors, and present your receipt and passport to the counter to get reimbursed. In some other stores advertising "duty free" (免税 menzei), you just present your passport to the cashier when making payment and the tax is deducted on the spot. When making tax free purchases or tax refund claims, counter staff would staple a piece of paper in your passport, which you should keep with you until you leave Japan. This piece of paper is to be surrendered to the customs counter at your point of departure just before you pass through immigration and checks may be done to ensure that you are bringing the items out of Japan.