The only site I could find where they listed an artist credit for this album art was on the YouTube video of the musicians recording some of the music for the album: https://www.youtube.com/watch?v=_1rhjCUt8wQ It could have taken some time to find the right artist tag without that annotation.
I like how this artist draws the muscial instruments pretty accurately. It's possible to varnish a violin green, but it certainly isn't common! You normally don't play that far down over the fingerboard unless you are trying to play very softly. Most of the bow action happens between the bridge and the fingerboard. Alternately, Nitori could just be resting the bow there before starting to play.
