UPDATE (December 5, 2012): For those interested, you may purchase this song from iTunes. And here I discover that the singer is Frida Lyngstad of ABBA (!). EDIT: That looks like a blunder from the iTunes store, since the singer is credited to Frida Sundemo.
Here is a set of videos containing the Mellsavon CM, with music by Kanno, featuring the light, relaxing vocals of Frida. Don’t forget to check it out also in Grand Funk for a much clearer and longer version of the song.