5

Maybe 500k, at best.

I think it will depend on if Microsoft will take this region more seriously. I found this article on VG24/7 they interviewed 2 Japanese indie developers about their views. It is very informative although somewhat of a long read.

http://www.vg247.com/2013/10/04/what-does-japan-really-think-of-xbox-one/

Some interesting excerpts from the article:

Incredibly, Xbox 360 is seen as something of a hardcore import machine that is played by the minority, rather than the widely-accepted juggernaut we see here in the West. Sak said, “Core gamers love the Xbox 360. They find its underground feel attractive. I’ve bought imports through Amazon, but I’ve never seen imported Xbox 360 games in normal video game stores. Mainstream gamers don’t buy import games.

“It’s fair to say that Xbox 360 players in Japan are generally either core gamers or people who obsess over particular game characters. The latter are people who bought an Xbox because of games like the Idol Master series or Steins;Gate. Most mainstream gamers see the Xbox 360 negatively as ‘an underground games system for core gamers’.

It almost sounds that Xbox systems in Japan are comparable to, say, the NeoGeo was here in the UK. It was an expensive system to import back in the day, and even if you had one the games would run you several hundred pound a pop. If you had one you were either seen as a hardcore purist or a silly sod with too much money in your back pocket. It’s little wonder that Xbox 360 has remained a niche format in Japan, given the cost involved when obtaining code.

So there you go, the view of the 360 was that people who were serious about gaming, or had money bought it. Hardcore niche gamers owned the system.
Sales of all next gen systems in Japan, that even the casual gamer has no interest in console gaming much either. I think Nintendo will continue to hold that area over Sony, just because Nintendo is the best 1st party developer of casual, family friendly games.

At least one, I'll be buying a second when they launch

Considering how bad japanese market is for home console right now, and considering japanese people will prefer to buy a similar product (PS4) from a japanese company (as they did in the past), it is difficult to be optimistic in any way for XBO in japan...

My guess would be 1 million LT.

Under 500k...

500k

Wow some vote 6m+

500K-1 million probably, which will probably be the same case WW. More than Xbox but less than 360.

100K< Lifetime Xbox One sales in Japan< 500K