I’m not sure why Nintendo doesn’t release these types of games in the US, but I’m considering getting a Japanese 3DS just to get this thing.
Daigasso! Band Brothers P
You can use youtube’s translated subtitles to get the gist of what the narrator is saying about the game, as well as read this great write-up about it at Nintendo World Report, for a more in-depth description.
My take on it is this game looks completely amazing, it has a story mode where you snap your pic and record your voice (which gets turned into a vocaloid <3 <3 ) then allows you to jam along to songs using a variety of instruments in single or multi-player mode. You can connect up to 10 3DSs and all play together which sounds like an amazingly chaotic and fun time. There’s also a huge library of J-Pop included, as well as “radio stations” that allow you to get a lot more.
In addition to all mentioned above, you can also compose your own music using a suite of tools built into Band Bros P. Once you’re done with those, you can share them with your friends via streetpass, and upload them to the Band Bros page where users can vote on them and download them. I spent some time on this page myself and found quite a few really awesome and cute chippy/Vocaloid-y songs, like the one linked above. Too bad I can’t really read Japanese to fully enjoy these sites, but either way this is some cool cool stuff from Nintendo!