I just found this in my Code Geass soundtrack. It's not in any of Hitomi's albums so I didn't know about it all this time! There's only a small sample of her voice but it's exceptionally calming and nostalgic (and thus really fits well with the title).
[video=youtube;eKyafFLW6fU]http://www.youtube.com/watch?v=eKyafFLW6fU[/video]