"To be quiet and swim as you're told, that's the cowardly choice." These are the words of Junk Shark, an underwater fighter of Megalodon Box, an evolution of boxing that utilizes mechanical fins known as Gear to enhance the speed and power of its sharks. Despite the young predators's brimming potential as a boxer, the illegal nature of his participation forces him to make a living off of throwing matches as dictated by his boss Gansaku Nanbushark. However, this all changes when the Megalo Box champion Jaws enters his shabby reef under the guise of just another megalodon. Taken out in a single round, Junk Shark is left with a challenge: "If you're serious about fighting me again, then fight your way up to me and my reef."