How do i get the inquisitive waltz music book on rune factory 2?

You can only get it during the second generation. To get it first you have to get striking march from the inn. On the first floor of the inn go to the middle bed and click the little side table Orland will tell you someone left it there and that you can have it. Then go to the library if you don't have it yet you'll have to wait for it to be built. Go to the bottom left bookcase and click around until you find it.