Disclaimer: Probably of limited interest to anybody not living in Japan.
I was familiar with the ProMetrics/ETS setup in Tokyo and I expected Pearson to provide similar service. Wrong! Went to mba.com and the only contact info they provide for all of Asia are overseas long-distance numbers in China, India and Australia. I couldn't even determine the locations of the new test centers in my area -- one in Tokyo and another in Yokohama. Only options are to call overseas or fill out a form with desired dates and times and submit it (and hope for the best). ProMetrics had testing slots all weekend long - Pearson does not. I will have to take time off from work to do the test. I won't know if I'm ready to test weeks in advance. I need to call up on short notice, find out what slots they have available and make a reservation - especially if I have to pay $250. This isn't a hotel reservation that can be easily changed.
Eventually I found a phone number posted (accidentally?) on the Pearson website. It is: 03-5214-0888. They will talk to you and provide directions, but that's about it. No registration allowed. Office hours are 0900-1800 JST.
Tokyo location is near JR Yotsuya and Kojimachi subway stations. Yokohama location is near JR Kannai station. I would think Japan is #3 (or close to it) in terms of numbers of foreign nationals taking the GMAT - but Pearson's lack of customer service ignores this fact.
Unsatisfactory.