As others noted, you will not have opportunity to buy duty free at Narita.

Even if it were possible, I would not recommend it. The duty free shops at Narita are no bargain when it comes to alcohol. Regular Japanese liquor stores sell it much cheaper than at Narita and with a much greater variety of product.

I was surprised to see decent Scotch available in Japan for about 1/2 of what I pay here (Canada). (But I always like to give the Japanese brands a try when over there)