The series was created in commemoration of the 50th anniversary of the boxing manga Ashita no Joe. Set in late 21st century Japan where boxers wear exoskeletons to fight. The narrative focuses on an underground fighter only known by his ring name Junk Dog, who decides to enter into a boxing competition called Megalonia. A second season, titled Megalobox 2: Nomad, aired from April 4 to June 27, 2021.