As deemed by Wikipedia (which I realize is not the most reliable source ever... but regardless) the Tone, Yoshino, and Chikugo rivers are Japan's "three greatest rivers". What makes them so great?
Light blue, is the most relaxing you can get. I would suggest a basic color theme of white and sky blue for your entire room.
Or you could go with the "warm relaxing" feel, and paint your walls some kind of honey golden color.