Proper Japanese Title: ビッグコミックオリジナル
Big Comic Original in its first incarnation (found here) was launched as a special issue of Big Comic. There is no clear difference between the issues of that magazine or this (serializations continued uninterrupted and no new ones were started in the first issue) except that those were officially numbered as issues of Big Comic while these began their own unique numbering. Both Big Comic and Original are semi-monthly and release on alternating dates of the month (10th and 25th for Big Comic, 5th and 20th for Big Comic Original). Original has some crossover authors and a lot of design similarities but is not aimed directly at the same audience as Big Comic and has in recent decades been the more mainstream of the two (and the top magazine in the Big Comic family by circulation).
Like Big Comic itself, Original has had quite a few decades-long franchises from legendary mangaka. Examples include Haguregumo, Abu-san, Tsuribaka Nisshi, San-Chōme no Yūhi: Yūyake no Uta, Kaze no Daichi and Tasogare Ryūseigun. Many of these works and authors are unknown to English audiences but in later decades it has also featured some major works by more internationally-known authors like Naoki Urasawa and Nobuyuki Fukumoto.
The cover design has consistently remained animal-themed though the artistic style or types of animals has changed in different periods. As the covers do not reference the manga contents or current events, occassionally an old cover has been reused.