This game is quite hard to get, being a Japanese only release, but is available through import on Amazon.com. I was weary playing a game in a language I didn't understand, but a few minutes aftrer the game was in my DS I was hooked!
The game is entirely in Japanese, but it's easy to understand with common sense. The menus will take a few tries to figure out, but that's the most trouble that I have had with it.
The game's concept is very different and addicting. You have to click on circles, spin spinners, and follow phrase markers to the beat of the music. The soundtrack, obviously, in all Japanese as well, but isn't difficult at all when it comes to keeping with the beat.
The game is very addicting and is definetly worth the import for any Nintendo DS/DS Lite system out there.