Apple's (AAPL -2.19%) share of the smartphone market has been limited by the growth of Google's (GOOGL -1.82%) Android -- the rapid adoption of Android in emerging markets has taken its toll on the iPhone's global market share.

Nevertheless, Apple has remained in control of one market -- the U.S. -- and looks to be adding a second: Japan. While the iPhone's growth in the one of the world's largest economies may not be ideal for Google, Sony (SONY -2.01%) could wind up being the biggest loser.

Apple is taking over the Japanese smartphone market
Apple has about 37% of the Japanese smartphone market right now, and analysts believe that number could approach 50% next year, according to The Wall Street Journal. NTT DoCoMo, Japan's largest wireless carrier, had avoided offering the iPhone until recently, selling its first Apple smartphones in September. Other major Japanese carriers countered with aggressive subsidies, offering the high-end iPhone 5s at no up-front cost.

As the WSJ notes, Samsung has never really been a major force in Japan, as Japanese consumers seem to have a bias against the Korean company. Although Google has other Android partners, Samsung is by far the most important; research firm Localytics estimates that nearly two-thirds of Android smartphones are now made by Samsung.

Japanese consumers are wealthy and loyal
Japan, being the world's third-largest economy and one of the wealthiest nations on the planet, is obviously a key market. Taking control of Japan could mean that Japanese video game developers focus on Apple's mobile platform over Google's, important given that nearly 40% of the time users are on smartphones they're playing games, according to research firm Flurry (via Business Insider).

But with Android now controlling more than 80% of the global smartphone market, Google need not worry too much about Japan. Rather, the company that seems most at a disadvantage is Sony.

As Japanese consumers have shunned Korean tech companies, they've remained loyal to their native corporations. Despite accounting for about 70% of the MP3 player market and dominating nearly every geography, Apple's iPod was, for a time, outsold in Japan by Sony's Walkman.

As other businesses have struggled, Sony shifts to mobile
Sony makes a diverse range of electronics, but many of its business units have begun to struggle. Its TV division has been unprofitable for most of the last decade, while its PC and camera sales have fallen.

To engineer a rebound, the company is banking on mobile devices, hoping to offer expensive smartphones that will compete head-to-head with Apple's iPhone. Sony's Xperia smartphones and tablets are among the most high-end Android devices on the market, but have so far seen limited success.

Sony still expects to sell 42 million smartphones this fiscal year, but could have some trouble reaching its goals with Apple moving into its home market so aggressively. With Apple and Samsung collectively dominating the U.S., Sony has said it will focus its smartphone efforts on Europe and Japan.

That's what makes Apple's growth in the Japanese market so devastating for Sony -- even with a slate of high-end devices, a focus on Japan, and a loyal consumer base, Apple appears to be taking over Sony's home market.

If Sony can't beat Apple in Japan, can it win anywhere?