It's an uphill battle that's been getting steeper the longer Xbox has been in the marketplace.
Xbox doesn't sell over there cause it's well-established it doesn't have a place, and it's a self-fulfilling prophecy of "Xbox can't sell cause MS needs more japanese games" > "MS management says no to subsidies/covering costs of porting games/moneyhats to Xbox because the audience isn't large enough" > "Xbox can't sell cause..."
If those rumours of MS thinking about acquiring SEGA had come through (before the original XBOX was announced), I think that would've given them a legit foothold in that region, but again, as years go by, MS is less-inclined to burn money on a department they aren't even confident in with regards to returns.
It doesn't matter if Xbox gets Final Fantasy or Tekken, because a few high-profile titles means nothing when the majority of japanese games are almost-automatically going to be developed for PS4/Switch/PC.