Hi no Tori

Hi no Tori (1956-57), is Osamu Tezuka's second crack at its concept. When it came time to work on a new series as a follow-up to the very popular Ribbon no Kishi (1953-56), Tezuka decided to return to the story begun in Hi no Tori serialized in Manga Shonen (1954-55)—one that had been abruptly cut short by the sudden demise of the magazine a year earlier. However, instead of simply trying to continue the story from where it had been left hanging, Tezuka decided to reboot the series completely. Drawing, the chapters "Egypt, Greece, and Rome," with its setting in ancient Europe, Again, however, this was never completed.
(Source: tezukainenglish.com)