This is not any music. This is Childhood's theme. Not my childhood, Childhood. Awe, wonder, curiosity, innocence, no responsibility. That stage of life when you're nothing other than a beholder of the universe.
I don't know how this style is called, but it has this Professor Layton-y sound to it, this calm enigmatic discovery-filled sound. The music box, the typewriter, the accordion... I purely love it.