It's going to be the same as 3ds vs Vita this time for Switch vs PS5. 

PS4 got lucky WiiU and DeadBox were the opponents in the Japan home console market. 

Cheeky bastard, I spat out my coffee at "Deadbox". XD

As I understand it, it's largely down to lifestyle; the Japanese work very long hours, so a portable system is more convenient for them because they can play it on their commute as well as just during the very brief amount of time they have at home and not sleeping.

Luckily the rest of the world stepped up. Japan's importance as a market for home consoles has severely diminished. Japan went from being responsible for 21.1% of PS1's to just 8.2% of PS4's, with the PS4 being the more successful product.

Same with Nintendo, 34.9% of SNES's were sold in Japan, only 12.6% of Wii's.

Once the PS4's sales finish, even without the Japanese region sales at all, it will still end up as the second best selling home console of all time. That's pretty crazy. How times have changed.

PS4 : Japan - 8.56m, ROTW - 18.48m.

That PS4 has sold over twice as many units in ROTW than Japan is also crazy...

I think it also has a lot to do with the increasing domination of the home console market by Western developers, and Japanese companies finding it harder to compete in that market.  A lot of them focused on the handheld market because doing so reduced development costs, and western developers generally didn't make big investments in that area.  

Percentages by region of the lead console is kind of a bizarre way to analyze things.  It leaves out a number of important factors.  Most notably, you're ignoring the fact that the next closest rivals to the PS1 and SNES sold really poorly in Japan.  The Sega Genesis and N64 were moderately popular outside Japan, so they reduced the SNES/PS1 market share in those areas, which increased the SNES/PS1 market share in Japan.  The US portion of NES sales was 54% to about 44% for the SNES, but that didn't mean the US home console market was shrinking.  Just that Genesis was taking up a big chunk of that market.

SNES + Genesis sales=20.6 million N64+PS1 sales= 27 million.  Wii sales + PS3 sales= 23 million.  So from the SNES to the Wii, the amount of consoles sold actually increased, but it was just split more evenly between the two main consoles whereas the SNES was essentially unopposed.  There's really only a massive drop this gen if you look at the Swtich only as a handheld.

I can testify to that... Been there recently and since transportation is highly developed, Japanese always favour public transportation rather than using cars. This gives them an opportunity to keep working, or use mobile devices.

I think the same of Westerners that don't like Nintendo because the "graphics aren't good enough" or 'it's just for kids". Also great games they're missing out on. Oh well, people like what they like I guess.

The Atari 2600 was the best selling console of its time. It sold unheard amount of units, way more than the closest competitor. It sold 30 millions. The Xbox One sold more than 30 millions so it should be a bigger success.

It's not like portability is the only factor at play though.

The other big one is the games. You can't play Splatoon 2, Smash Bros Ultimate, or Pokemon Sword/Shield on Playstation 4.

TOP 10 Switch Famitsu 2019:

1. Pokemon Sword / Shield - 2.456.459
2. Smash Ultimate - 1.022.927
3. Super Mario Maker 2 - 739.734
4. New Super Mario Bros. U Deluxe - 723.501
5. Mario Kart 8 Deluxe - 549.994
6. Minecraft - 538.091
7. Dragon Quest XI: Echoes of an Elusive Age S - 449.475
8. Super Mario Party - 432.167
9. Pokemon: Let's Go, Pikachu! / Let's Go, Eevee! - 420.791
10. Ring Fit Adventure - 386.257

TOTAL: 7.719.396

Top 10 Switch Famitsu CY2018:

1. Super Smash Bros. Ultimate - 2.360.655
2. Pokemon: Let's Go, Pikachu! / Let's Go, Eevee! - 1.253.677
3. Splatoon 2 - 1.122.324
4. Mario Kart 8 Deluxe - 926.553
5. Super Mario Party - 764.853
6. Kirby Star Allies - 664.815
7. Super Mario Odyssey - 575.926
8. Minecraft- 525.045
9. The Legend of Zelda: Breath of the Wild - 491.648
10. Mario Tennis Aces - 376.366

TOTAL: 9.061.862

• Pokemon Sword/Shield has surpassed Smash's total sales for 2018, with the biggest week of the holidays coming up. Looking like 3M physical at Week 1, 2020 
• Expecting Pokemon Sword / Shield to sell around 300K to 350K next week. Ring Fit Adventure to sell 125K to 200K(depends on shipment), Luigi's Mansion under 100K
• With a big shipment for Ring Fit Adventure for the holidays, it should catch up to MK8D and Minecraft by the end of 2019
• Luigi's Mansion 3 should also make the top 10 knocking out Pokemon Lets Go
• 1.3M software sales needed to surpass 2018, this week the top 10 sold around 400K, last year Switch sold >1M Software in Week 51
• Next week Switch Software should be between 750-900K since this year Week 52 will be slightly stronger and Week 51 slightly weaker

So true. What are the monster franchises outside of Nintendo first party? Monster Hunter and Dragon Quest?

While Nintendo-only monster franchises in Japan are: Splatoon, Mario Kart, Smash, Pokemon, and Animal Crossing. And maybe Mario as well.

And with Dragon Quest finally hitting the Switch and I can only assume being developed with Nintendo's systems first in mind from here on out, the only mega japanese selling franchise they are missing is Monster Hunter. It'll be interesting to see if Switch starts being the target for Monster Hunter or if Capcom sticks with wanting to sacrifice sales to make the most powerful game they can make.