Exchange Order late arrival

Hello,

We are a bit late in our trip organisation and wanted to ask if it's better to order our ticket now or buy it directly at the airport. We will be arriving in Haneda Terminal 3 on the 29/09. I'm afraid that our exchange order might not arrived on time before we leave Germany on the 28th (would be around 7 working days). However with the prices going up I've read from sources that some ticket centers might be closing before the 01/10 because they are overwhelmed from demands, preventing us from being able to buy upon our arrival in Japan.
If we order it now and the exchange order comes too late, can we ask for a refund once we come back to Germany after our trip ?

Thank you for all your tips