Best rate is always just using your debitcard to withdraw from any compatible ATM in Japan. I have an extra bank that takes no currency surcharge or ATM fee when withdrawing in foreign currency. Exchange booths will always rip you off in one way or another.
Thank you so much for the informative video sir. What if the arrival time at the airport is outside the window during which the shop is open, is there another way to exchange money 24/7 ?