I travelled to Japan last year and bought some stuff from shops in Tokyo which were subject to return of consumption tax (GST). However, I forgot to submit those consumption tax receipts (which the shop cashiers attached to my passport) to the customs counter in the airport when I exited back to my country. What shall I do now? Will I be blacklisted and refused entry into Japan when I visit Tokyo again sometime in the next few months? Do I need to pay a penalty, and if so, how much?
Don't worry about it. Because there are no electronic records for tax-free purchases, Customs does not know that you were supposed to show them, and as far as I can tell there is zero enforcement of this.
The theoretical point of the system is to ensure that you're taking the duty-free item out of the country, and because you did, you're OK.