Shiroi Koibito park prices vs airport prices

Is it cheaper to buy in Shiroi Koibito park or at the airport?

Cheaper at the airport. No tax free at Shiroi Koibito Park.

Shiroi Koibito park is a great place, a bit bizarre from a western point of view, but not nearly enough for me to want to visit a third time sometime in the future.

I do know that it is not the only factory for the biscuits, and while I'm not sure that it is guaranteed, if you want to bring back an omiyage for someone who cares that it was made there, it's probably better to buy at the park itself. I don't doubt that the products at the other factory are just as good though.

Having said that, I'm not the sort to care about a 10% difference in price on something like this, given that sales tax/VAT is 20% where I live. Also, the duty free shop may increase the price to negate much of the saving (might be more of a Europe/US thing).