As Zelda fans know, The Legend of Zelda games don’t tend to sell very well in Japan as compared to the west.
It seems The Legend of Zelda: Breath of the Wild is going to mark a huge sales milestone soon, thanks to the observant Japanese commentators on 5ch. The Switch version of Breath of the Wild has sold 802,811 physical copies in Japan up till January 7, 2018 (this comes from Media Create), and the Wii U version has sold 133,024 so far (this comes from Nintendo’s IR website).
Adding both figures together gives Breath of the Wild 935,835 copies sold in Japan. As the game is still selling strongly on Switch, we expect The Legend of Zelda: Breath of the Wild to cross 1 million copies in the next few weeks.