Hyakutarō Senjū commands the Adachi Tribe as both leader and ace pitcher, steering a band notorious for their raw power and unyielding ferocity. The tribe claims dominion over a dilapidated enclosed shopping arcade in Tokyo’s Adachi ward, transforming it into their home field for brutal clashes. Armed with custom XB Gear—a bat and ball engulfed in flames—he champions Extreme Baseball (XB) as a primal, unrestrained trial of strength between tribes, demanding absolute resolve and merciless annihilation of foes who falter.

His strategy hinges on fiery spectacle and brute force, leveraging incendiary tactics to crush adversaries through sheer intimidation. Paradoxically, though leading a biker gang, he spurns motorcycles, navigating the streets on a humble bicycle—a quirk that sets him apart from his roaring comrades.

A familial thread weaves through his story: his younger brother, Hyakuichitaro Senjū, stands as a playable figure in Tribe Nine’s roster. While their shared history remains unexamined, this bond subtly anchors Hyakutarō’s identity beyond the battlefield.

His existence revolves entirely around the Adachi Tribe’s dominance and XB’s dual role as symbolic ritual and visceral combat, with no documented lore extending beyond his iron-fisted leadership and fervent devotion to the game’s lawless ethos.