Japan loves portability. You can't whip out an Xbox on a bullet train. Playstation and Nintendo both have portable systems which sell really well. Even though PS has started to abandon Portability, the popularity and PS+ accounts remian. Playstation already had an in before Xbox even came to Japan. The PS1 released in 1994, and the PS2 released in early 2000. Nearly 2 years before Xbox! Why bother getting a second console? Playstation has exclusives of popular Japanese games like Dragon Quest, Monster Hunter (not anymore), Final Fantasy, Kingdom Hearts, etc. etc. When all of the most popular games are on Playstation and only a few FPS games and racing games are on Xbox, why make the switch? Xbox couldn't get its foot in the door early on. In order to achieve mass popularity NOW, they'd have to somehow provide an experience that's infinitely better than anything Playstation can give. Game Pass attempts that, but they still need to get the word out better.
They're probably gonna angle xCloud for the Japan. Probably would work really well with their internet.