Game: Tomodachi Collection (トモダチコレクション)
Platform: Nintendo DS
Music by Daisuke Shiiba, Ryutaro Takahashi, Riyu Tamura and Asuka Ito

Music originally uploaded by Ninty89, but the original video was taken down by Nintendo.
Here's their Youtube channel if you ever want to listen to other obscure video game soundtracks while they're still up:    / channel  

Tomodachi Collection OST Playlist:    • Tomodachi Collection OST (Complete)