I doubt gamers in Japan will want anything xbox has to offer. I mean the 360 was not very popular in Japan (it sold 1.6 million units in it's lifetime compared to 9.9 million PS3s). And that's not likely going to change for this generation without some radical switches taking place (and I just don't foresee them happening).
In all likelihood Japanese gamers that want KH3 or FF15 will buy it on PS4.
And right now the reason sales of PS4 in Japan have slumped is likely because they're waiting for more big name games to drop.
In all likelihood Japanese gamers that want KH3 or FF15 will buy it on PS4.
And right now the reason sales of PS4 in Japan have slumped is likely because they're waiting for more big name games to drop.