I donno... 4 key is too easy, I'd rather just listen to the song...
have u been trying to unlock everything in that game tho, Charanca???
It's too hard~!!! I do not recommend it, and I don't think anybody else does either....
if u havent, u should download the complete save file from gamefaqs and load it to your mem stick.
It will erase all your high scores, but they will all be reset back at 0 (i.e. you won't see somebody else's hi scores)
that way all artwork, songs, gears, & notes are unlocked for u and u don't have to struggle for them