This really reminds me of the N64/GCN in Japan, lol, where occasionally they would get a big bump and Nintendo fans would claim momentum was coming back in their favour. Which obviously never happened. It's interesting to see Sony now in that position. How the mighty have fallen. What's particularily funny is SEGA being cast as the one to "save" a floundering Sony platform, lol (the PSOne must be rolling around in its grave somewhere).
Also seeing no other Vita games get a bump into the top 30 indicates in Japan a lot of people probably bought the system/game with the intent of selling it back once they're done with the one game (this happens a lot over there).
The fact is if I'm a Japanese publisher and I'm looking at this market, the 3DS still has a way bigger userbase and is cheaper to develop for and can do reasonably decent 3D graphics. Where's the appeal in Vita? The Sega developers apparently are not happy with these sales because the development cost was high, which really indicates a weakness of the platform.
I don't think Monster Hunter is going anywhere until at least Monster Hunter 4 has come out and already moved the remaining MH audience over to the 3DS. People need to stop looking at MH at some shining horse for the Vita, Capcom has no obligation to help Sony out when they can't sell their own system.
