Beside the prominent entrance to Kansai International Airport's Terminal 2, which serves several budget airlines, is a nondescript door to which a sign saying Premium Gate Tamayura has been affixed.

This is the entrance through which the world's rich and famous enter to access a small, quiet lounge with an adjoining area for customs and immigration. From here, they can quickly go through the necessary formalities in a fraction of the time it takes passengers on commercial airline flights.

It was this lounge, which is closed to the general public, that former Nissan Chief Executive Carlos Ghosn reportedly entered and exited when he was smuggled out of Japan last month on an Istanbul-bound private Bombardier jet — purportedly in a large audio equipment box that wasn't inspected before loading.