Although Japan is a relatively small market on the global scale, with only about 3.6 Million total tablet sales last year, today's news is still fairly significant and Apple will surely be taking note. Reportedly, the Google Nexus 7 dethroned the iPad as the number one tablet sold in the "land of the rising sun." Here's a quote with some of the details,

Nikkei cites market research firm BCN in reporting that a survey of 2,400 stores across Japan suggests that Google’s 7-inch tablet accounted for 44.4% of all tablet sales by large electronics vendors in the region. Despite the launch of the iPad mini, sales of Apple tablets were said to account for 40.1% of all tablet sales over the period. It is unclear if Apple stores were included in the firm’s poll.

Google’s Nexus 7 is designed as a land grab and in Japan, it is clearly working in that regard. Nikkei notes that the Nexus 7 costs 19,800 yen in Japan, compared to entry-level prices of 42,800 yen and 28,800 yen for the iPad and iPad mini, respectively.
So, now that the Samsung Galaxy S III has surpassed the iPhone in sales globally, and the Google Nexus 7 has just started to outshine the iPad (albeit on a smaller scale), could it only be a matter of time before Apple finds itself as the "niche" product again, just like in the old days of Microsoft vs. Apple?

Source: BGR