iPhone 6 Japan
People try out the iPhone 6 and 6 Plus at the Apple Store in Tokyo's Omotesando shopping district. Reuters

In the first week after launch, Apple’s iPhone 6 and 6 Plus are dominating mobile sales not only in the United States but also in Japanese markets. Unlike China, Japan was part of the iPhone 6’s initial launch group, which contributed to a combined 10 million iPhone 6 and 6 Plus units sold in its first three days.

The iPhone 6 and 6 Plus were the top-selling phones at Japan's three major wireless carriers, and iPhones (including the 5S) from various carriers held the top 18 spots in overall sales, according to rankings provided by BCN, which track smartphone sales on a weekly and monthly basis.

Japan’s SoftBank took the majority of iPhone 6 and 6 Plus sales with 42.9 percent of the weekly share, followed by KDDI mobile brand Au with 32.2 percent and NTT DoCoMo with 24.9 percent.

iPhone 6 BCN
BCN's breakdown of iPhone 6 and 6 Plus first week sales in Japan BCN

The smaller, 4.7-inch iPhone 6 took the bulk of the new-Apple-phone sales with 82.2 percent, leaving the larger 5.5-inch iPhone 6 Plus with a 17.8 percent share. This follows a similar trend in the United States and Europe.

This may be in part due to production constraints and low display yields that have largely left the iPhone 6 Plus in short supply online and in retail stores.

“While our team managed the manufacturing ramp better than ever before, we could have sold many more iPhones with greater supply and we are working hard to fill orders as quickly as possible,” Apple CEO Tim Cook said as the company announced the iPhone 6’s weekend sales record on Monday.

Despite Apple’s ambitions to fill orders quickly, its online stores continue to see shipping times of as long as 7-10 days for the iPhone 6 and 3-4 weeks for the iPhone 6 Plus. The company will expand iPhone 6 sales to 20 additional countries on Friday.