Xcloud (cloud gaming) is not currently available in Japan.
https://www.xbox.com/en-us/regions?source=lp
Click on Gamepass and it shows Cloud gaming with an X in the JP area.
Also another thing going against it is that it is not currently available on iphone/ios. Even more so than the USA, the iphone is the dominant platform here in Japan.
https://www.pcmag.com/news/ios-more-popular-in-japan-and-us-android-dominates-in-china-and-india
Once it is actually available in Japan and you can get it on ios, then it should have more penetration. Possibly going through the web like Amazon with their Luna service which goes through the browser and not the app store.
I’ve been wanting to try it out myself as I have my Xbox account region set to the U.S. (not Japan), but since I use ios I’ve only been able to use the xbox app to stream from my Series X to my iphone. That worked fine connected to my Xbox one controller.
starcraft: "I and every PS3 fanboy alive are waiting for Versus more than FFXIII.
Me since the games were revealed, the fanboys since E3." 
Skeeuk: "playstation 3 is the ultimate in gaming acceleration"
