The Fatal Frame games on the PS2 have each iteration selling better than the last (at least from my quick check). That means that the userbase grew more and more accustomed to the game over time as the series become more familiar to the platform. I wouldn't really expect the Wii to have a higher launch for the game than any of the previous games on the PS2. Remember that a good bit of the Wii owners in Japan are likely Gamecube owners (the majority are likely PS2 owners though), and the Fatal Frame series, to my knowledge, was never on the Gamecube. The Wii audience is yet to fully capture the PS2 audience, and the traditional Nintendo audience isn't really accustomed to the series.
25-30k first week.