The Wii U launch for Japan is pretty strong actually, stronger than any recent product launch there IMO. Far better than the 3DS and Vita launches and probably a tad better than the Wii launch in 2006.
New Super Mario Bros. U, Nintendo Land, Monster Hunter Tri G Ultimate, and the free Dragon Quest X beta are fairly substantial.
Better than the Wii launch I think, Mario >>>>> Zelda, and I think Nintendo Land is going to be huge in Japan, people are underestimating that. Even Wii Party sold 1+ million in Japan with ease, the Nintendo theme park concept squeezed into a Wii Play style game is going to be huge there IMO. Maybe not quite as big as Wii Sports, but not far off either.
Monster Hunter won't have the impact of the handheld version, but it's still a solid release. People forget, it took 3 years for the Wii to get NSMB and even longer to get Monster Hunter Tri. Way too long ... that was the Wii's problem.
The other thing is with the Vita flopping and the PSP petering out, basically the opening for the "no.2 game system in Japan" is now wide open for the Wii U to take (3DS obviously will be no.1). If they can get off to a fast start and get more Japanese third party support faster in the system's life cycle, they could push Sony out of the market entirely.