That's the wrong read. It's more that it's easy to understand. "I will give you a 100 dollar bill, please give me a 10,000 yen bill."
If the guy was so hot to not lose a dime, he could have said, “Loan me 10k yen right now, I will pay you back ASAP”.
If the guy is in Japan with American currency, he likely knows the exchange rate and exactly the terms he was getting.