Question regarding Sigma Harmonics

I liked the look of this DS game but unfortunately it didn't come out over here so I was never able to see whether it was any good or not.

I've been searching for information and spoilers regarding the game's story but I haven't been able to find much information and what little information I have found and been able to deduce is not enough to produce a clear picture.

Is there anyone who has played the game and can tell me about the plot in detail?

I only know of the game through it's (awesome) soundtrack by Masashi Hamauzu. Looking at the track titles, I can see that it has something to do with time travel, but that's all I know. =d