Haru Shirokane and Taiga are saved from a group of delinquents by the strongest Extreme Baseball (XB) player and leader of the Minato Tribe, Shun Kamiya. Despite calling him boring, Kamiya invites Haru to his XB team with Taiga joining too. Suddenly, the Shinagawa Tribe's leader, Yutaka Gotanda, marches into Minato's hideout to challenge them to an XB match with their highly-developed XB gear. Shun decides to press Haru and Taiga into service immediately, giving them a crash course on the rules of XB, as Minato defeats Shinagawa by knocking out their leader.