This information comes from Nintendo’s investors briefing as stated by president Tatsumi Kimishima…

With respect to Fire Emblem Fates released in February, this graph shows a comparison between the total sell-through in the U.S. market and the total sell-through in the Japanese market, where the title launched earlier. The week of each launch is counted as Week 1.

Sales surpassed the 500,000 mark in the U.S. in Week 6 and have continued without losing momentum. Recently, sales caught up to Japan and are even maintaining a pace slightly higher than in the Japanese market.

This graph adds a comparison with the previous entry in the series, Fire Emblem Awakening. As you can see, there are major differences in the trends in the Japanese and American markets.

In Japan, most of the demand is filled within the first few weeks after launch, but the Fire Emblem series continues to perform well over a long period in the U.S.

In the past, the Fire Emblem series did not sell as well in the U.S. as it did in Japan. However, Fire Emblem Awakening greatly expanded the user base for the series, and the current entry, Fire Emblem Fates, has been popular abroad as well since launch.