Quite a simple formula, but very very very addictive...
Now I don't know a word of japanese, but one doesn't need to. All you need to know is that the top button of the menu takes you to the game :P Those silly "plots" of the songs will make themselves apparent via other graphical methods.
The music is way better than in the first one, this one has more of those "silly jpop tracks" which are catchy in their own way, you won't grow bored with them.
With plenty of difficulty levels (4 in total? At least I have 4 now), and nearly 20 tracks, Ouendan won't be done with after the first completion, ooooh no. Nuh uh. You are unable to change the game cartridge. "Just one more track!", you scream. Sure. This is a rare game, as you can just play it for the sake of playing, you don't need to accomplish anything new ingame to make the playing process feel good.
Import this game at all costs! I will propably never give any other game a perfect score, so...