All product price listed on Amazon.co.jp must include consumption tax, and must not indicate any tax excluded product price or tax excluded price combined with the tax amount.
Also, please note that it is prohibited under Act Concerning Special Measures for Pass-on of Consumption Tax ("Act") to display the product price indicating any deduction of all or partial amount equivalent to consumption tax customers are to incur.
Below are examples of prohibited indications:
Amazon.co.jp may report to the Fair-trade Commission, the Consumer Affairs Agency and Cabinet Office if any price display in violation of the Act is detected.
Please do not indicate as “tax free” or “subject to reduced tax rate” on the product detail pages on Amazon.co.jp. In accordance with Act against Unjustifiable Premiums and Misleading Representations (hereinafter referred to as “the Act”), representations that could be misunderstood by the general consumer as being significantly advantageous are prohibited as Misleading Representations. As Amazon.co.jp has the risk of violating the Act, do not indicate as “tax free” or “subject to reduced tax rate” on the product detail pages. Representations such as “tax free” and “subject to reduced tax rate” on the product detail pages may be deleted from those pages.
Act Concerning Special Measures for Pass-on of Consumption Tax (Japanese)