Just in! Opening sales for Breath of the Wild have outperformed Horizon Zero Dawn's sales in the Land of the Rising Sun. Knowing Japanese gaming trends, some might not consider this too much of a surprise. Enduring gaming trends in Japan have tended towards mobility for some time now and the Switch is perfectly capable of gaming on the go.
The Legend of Zelda: Breath of the Wild moved 193,000 units on the Switch and an additional 45,052 on the WiiU. Horizon Zero Dawn moved 109,739 units on the PS4. Recall that Switch has only just recently launched in Japan selling 330,637 of the units while PS4 has an install base of millions in Japan. Entirely possible that Japan prefers the artsy approach of BotW's aesthetic to HZD's more realistic one hence the sales numbers. After years of indulging in Japanese industries, I get the feeling Japan loves artsy things not unlike myself. Don't take my word for it though, it's just my gut feeling...
