As of the latest research from Nielsen, we know the United States smartphone market has quickly become an iOS/Android duopoly with 90 percent of devices on either one of those platforms. While smartphone usage in Japan is still at 1-in-5 mobile phone owners, new numbers from comScore today show Japan’s smartphone market is also quickly becoming dominated by Apple and Google. To be specific, 95.6-percent of smartphones in the country are Android or iPhone, and Apple has outgrown Google in the last three months while Android’s share remains steady.