I cannot comment on the cost of games in Japan, but I can say this.
The install base for the PS4 is abysmal in Japan, and while software might sell well in general, it would have to do an unprecedented job of selling consoles to make the Japanese market more relevant. The heavy hitters for Sony in Japan are FFXV and KH3. FFXV has me thinking it's going to flop quite frankly. SquareEnix lost their magic and the project's been in the works for almost a decade now which is almost never a good sign. It'll sell well in Japan, but it won't be as big as you'd expect. Kingdom Hearts 3 may suffer the same effect, but it does have a more rabid fan base that's starved for a true sequel.
I'm guessing FFXV will do well in Japan, but not as well as previous entries, and underperfom internationally. Kingdom Hearts will do good in spite of the series dying sales, because it is part of the main series. Sony will get respectable boost in Japanese sales, but probably won't overtake the Wii U in the foreseeable future.