Apple sold a record 13 million units of the iPhone 6S and 6S Plus globally on their opening weekend. But in Japan, sales of the smartphone were down by 10 to 15 percent compared to the iPhone 6 and 6 Plus launch last year, according to a BCN market research report cited by Digitimes.

Japan mobile carrier NTT DoCoMo pointed to strong iPhone 6S sales, but admitted that people lining up outside its stores for the iPhone were less than preceding iPhones, according to Digitimes. The carrier also noted that customers may have delayed their purchases since its stores announced when they will receive more stock of Apple's smartphone.

Despite the reported downturn in Japan iPhone sales, global weekend sales were up 3 million units compared to last year, in part due to China’s inclusion in the iPhone 6S’ launch weekend. Last year, the country was excluded from the initial iPhone 6 launch due to regulatory problems. But in the brief weeks that the iPhone 6 wasn’t officially available in China, those that didn’t want to wait were able to purchase the smartphone through black market smugglers. Not all of the phones made it through to mainland China, including 94 iPhones that were strapped to a man’s body.

Apple doesn’t breakdown iPhone sales by country. But Asian countries continue to be an important part of its sales growth.

“In terms of what's going on with iPhone, the 35 percent [unit] growth is almost three times the market,” Apple CEO Tim Cook said during a July earnings call. “And if you look at it at a little narrower regional level, Western Europe grew 30 percent versus a market of 7 percent, so four times market. Japan grew over five times market.”

Chinese iPhone sales accounted for 87 percent growth versus a 5 percent market growth, he added.

Driving Apple’s growth the most in Asia is China, which has an estimated 525.8 million smartphone owners, according to eMarketer. But that growth is starting to settle, as smartphone growth in the country is expected to slow to 1.2 percent down from 19.7 percent, according to IDC.