What actors and actresses appeared in Sora no uta - 1999?

There appears to be a misunderstanding. "Sora no Uta" is not a movie or TV show. It is a Japanese manga series, written and illustrated by Kaori Yuki.

It's possible you are thinking of a different title, or perhaps there's a movie or show based on the manga that you're interested in.

Please provide more details or clarify your question so I can give you a helpful answer.