The Nikkei is reporting that a recent report from the market research firm BCN suggests that the Nexus 7 represented 44% of tablet sales in Japan. The iPad came in second with a 40% share, the first time the iPad wasn't the best selling tablet in that market.
But before we get too excited about the iPad being dethroned, I think we need to take a second look at those numbers. These 2 tablets claimed 85% of the tablet market in this survey, and that doesn't leave much room for the Kindle Fire which we know had decent sales in the US this holiday.
Amazon launched the Kindle Fire HD in Japan late in 2012, so they might not have had much in the way of sales. But given the media attention lavished on Amazon's tablets, I would bet that Amazon sold more Kindle Fires in Japan than this survey suggests.
Assuming that this story came through Google Translate correctly, the original Nikkei story indicates that BCN's survey group only covers Japanese retailers, not consumers. It doesn't really describe the tablet market. Among the sites left out of this survey group are Amazon, Apple, and Google, so we really don't have any data on what was the most popular tablet in Japan these past few months.
This, folks, is how otherwise legitimate surveys can lie to you. It's also an example of why I like to look at the original source for stories rather than work off of a secondary source. In this case CNet beat me to the story but missed the important detail.