Haru Shirogane is a weak-minded person who is constantly bullied while Taiga has traveled from across the sea in hopes of becoming the strongest man in the world. One night, the two meet up with Shun Kamiya, the strongest XB (Extreme Baseball) player, and leader of the Minato Tribe. When they meet, each of the Tribes scattered throughout Neo-Tokyo are about to face a major threat.

On the orders of the King of Neo-Tokyo, "Houtenshin", the Chiyoda Try, led by the mysterious Ojiro Otori, has started to take control of all the tribes in the country. Their evil clutches are about to reach the Minato Tribe...