Designated procedures must be completed when applying for tax exemption (10%) on purchased products.

At the store

Foreign (non-Japanese) nationals who have entered Japan within the last six months (excluding persons working in a Japan-based office)
Tax exemption is not possible for persons who do not present their own passport.
In case using a credit card, the name on your passport must be the same name on your credit card.
Items purchased on the day of application are eligible for tax exemption.

At the airport

Please present your passport and purchased items at the customs in the airport when leaving the country.
Each country prohibits the bringing in of certain items, for example the items in violation of the Washington Convention (CITES)
So please check by yourself if the items are able bring back to your country.