Bofferbrauer on 18 March 2015
It's not just the Wii U though. While PS4 titles have much better first weeks, sales tend to drop like a rock, so much that very few PS4 titles even chart longer than 2 or 3 weeks. Only 3 million PS4 games have been sold in retail, less than 3 per console, and it doesn't look like this will change much yet. 33k PS4 sold and 118k retail games, so just around 3.5 games per console, 7k and 27k for the Wii U, which ain't much better percentage-wise and much worse in absolute numbers.
In other words, this seems to be more of a general trend in japan, which is most notable on Nintendos console but not exclusive to it.
