Purple and pink are my relaxation colors. No matter how many times I look at them, I never get tired so I look for sky like that, and ~~~ there it goes.

As for the message/quote, the "key"refers to key signature; and hopefully, the key (of my heart) could hear my melody.
Miyazono has that line too, although it was like this: "Will I reach you? I hope I can reach you."
and I say, she can reach that person through her music via sky. After all, we're under one sky.

I would like to extend my gratitude to the two sites below:
Miyazono: http://static.zerochan.net/Miyazono.Kaori.full.1787386.jpg
Background: http://freetopwallpaper.com/wp-content/gallery/sky/sky-wallpaper-hd-background-picture-2.png

Thank you very much!