Depends why the customer is mad. I seem to deal with a lot of incompetent Japanese people all the time and it is very difficult. I find that many people don't even know the company policy or they claim something totally different than what is stated on the company website. For example, I used Avios to book a Iberia award ticket on JAL. That was easy, however when I went to the airport I could not check in with the machine and needed to speak to a JAL rep. Well NO ONE had any idea how to look up my ticket or print my boarding pass. No one even know Iberia was a one world partner. It only took 4 reps, 1 manager, and 5 manuals to figure out how to print my ticket. This was after they tried to tell me my ticket was canceled. They also wanted to see a confirmation email in Japanese because they can't read or speak English.
Fair enough about not speaking English, but if your country (Japan) is trying to market itself to foreign visitors, perhaps you should speak a very widely used language like English!