AstroBoy Online Forums

I'm not sure I understand the Japanese description in this video even after using Google Translate (which I realize isn't the best translating source sometimes), but it seems to say that this song was a theme song written by Yasuo Higuchi for the 1980s anime at the request of Osamu Tezuka. Higuchi's song was never used, but it was later used to commemorate the 50th anniversary of Astro Boy in 2003.

Quite interesting, if I do say so myself. I still prefer the theme song that we got, but this one isn't bad. To think that we could've gotten a different theme song for the 1980s anime.

鉄腕アトム幻の主題歌