In 1974-1975 five months before the release of the anime Gamba no Bouken there was a newspaper “Yomiuri Shimbun” that published a version of the novel 冒険者たち ガンバと15ひきの仲間 (The Adventurers: Gamba and His Fifteen Companions) by Atsuo Saitoh.
Because the animation rights were sold to another studio it was canceled after only 7 numbers. https://twitter.com/mtsujiji/status/1519926401368948736
Scans from https://twitter.com/nfuJDsUmIJ0LEbd/status/1519683818541633537 https://twitter.com/nfuJDsUmIJ0LEbd/status/1520048599232524288 https://twitter.com/nfuJDsUmIJ0LEbd/status/1520055137074434050