Even with the Wii U failing globally, 3DS and onward have proven Nintendo grips Japan with an iron fist. PS4 sold about 0.9 million less in Japan than the PS3, meaning it couldn't crack 10 million.
For over 10 years, Nintendo platforms are on top and that likely won't change again. Sony had their dominance with the PS1 and PS2 and was competitive enough with the PS3 and PSP. But other than that, it's been Nintendo Land over in Japan.
And yeah, a lot of that has to do with the Japanese market enjoying handhelds more than a lot of other markets.
Lifetime Sales Predictions
Switch: 144 million (was 73, then 96, then 113 million, then 125 million)
PS5: 105 million Xbox Series S/X: 60 million
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima