curl-6 on 19 September 2019
As of this week's numbers, Mario Odyssey has sold over 2 million in Japan alone, making it the 4th Switch game to cross this threshold after Smash, MK8D, and Splatoon 2
https://gonintendo.com/stories/344936-super-mario-odyssey-sells-2-million-physical-copies-in-japan-alon