You are Comparing Life-time sales with my comparison about 2 years sales, the Playstation 4, still had the Wii U on japan, the console would not be dying if Nintendo, had made a Re-stock, and running for Third Party Support, overseas we had the Xbox 360, having a lot of sose artucess, and was a competition for Playstation, and still had the Wii, on Japan you only had PS3, and Wii, but you also had 1.2 Millions of Xbox 360.
Japan's Last gen sales numbers was 24-25 Millions total of Home Consoles sold, Nintendo NX, will still be a Home Console of the 8 generation, and Playstation 4 Sales will raise, i'm sure that this Generation life-time sales will be bigger than 24-25 Millions on Japan.
You also forgot that the PS3, was selling half of the Playstation 4, until recently, now the sales have stopped, and Playstation 4, is getting momentum.
This fail in Sales is because of the Handheld market, those articles about "24 Years Low" they count the Handheld market, previous gen the Nintendo DS, and the PSP, sold 53 Millions of units on Japan, now is less than 27 Millions and we are on the last years of the Handheld generation.
The Home console market on Japan still big, even if it falls the same every year, will take years for someone to take Japan's Place, as the second biggest country for Console Gaming, you can Spin it how much you want, but now, the Present day, Japan is Much bigger than any other country, with the exception of USA, for the Console Gaming.
Germany's Last gen numbers are 12 Millions of Home consoles sold in total, something like this 12-13 Millions, this is 50-55% of what Japan Did.
France's Last gen numbers are 15.6 Millions of home consoles sold in Total, is 60% of What japan did.
Now the numbers are, France with 70% of what japan did, and Germany, with 75%.
We still don't have a main Final Fantasy game, neither a Dragon Quest game, so wait atleast after Final Fantasy XV's Release, after that you can argue.
at this time in the gen Japan had 2 times the numbers of home consoles sold that it is, but Xbox 360, was not a failure, and Wii, was a monster.
the Wii, sold 60% of his life-time sales on japan in the first 2 years, the Playstation 2, only passed the 10 millions mark in 2014, 4 years after Wii, did it, and the 2 ended up selling nearly the same on Japan.
We are talking about Home console market, you say that the market is dead and only use Playstation, to state that the Whole market is dead, since the 7 Generation, Nintendo is a Equal rival for Sony.