In the late 21st century, a sport called Megalo Boxing has emerged where fighters wear powered exoskeletons known as Gears. An underground fighter called Junk Dog makes his living by throwing fixed matches in illegal rings, longing for a real fight. After a fateful encounter with champion Yuri, Junk Dog decides to enter the prestigious Megalonia tournament under the name Joe. Fighting without any Gear and earning the nickname Gearless Joe, he battles his way through ranked opponents to prove himself and face Yuri in a legitimate match, all while dealing with the dangerous underworld that controls his fate.