Sheyenne Rainstorm, once a nomadic gunslinger of renown, mastered ARMS—a rare, formidable weapon system. Ambushed and mortally wounded, his consciousness was transplanted into a synthetic body mirroring a ten-year-old’s frame, preserving his adult mind while his original form vanished. Revived in Alcatraz prison’s depths, he joins Dr. Kiel Aronnax and thieves Loretta Oratorio and Mirabelle Graceland during their jailbreak. Driven to reclaim his stolen body, he travels with Kiel’s crew, grappling with the dissonance between his youthful appearance and his former identity as a charismatic playboy, whose charm once lured admirers effortlessly.

Confident and quick-witted, Sheyenne flirts unabashedly, sparking friction with the brash Loretta. His combat mastery centers on the Batour—a morphing ARMS weapon progressing from pistol to rifle, then gun emplacement, and finally a life-threatening cannon whose apocalyptic discharge risks killing its user. Despite his unfamiliar physique, his sharpshooting precision persists.

A back birthmark and immunity to ARMS’ corruption fuel whispers of his ties to the Evil Race, ancient adversaries of the goddess Daigan. He weaponizes these rumors, unnerving foes with veiled threats of dark allegiance. Tensions simmer with Mirabelle, whose vampiric kin crave his unique blood, though his obsession with recovering his body overshadows personal entanglements.

The hunt for his physical form unravels larger enigmas: ARMS’ origins and their role in Filgaia’s destiny. Allies like the principled yet conflicted Kiel and self-serving treasure hunters complicate his mission, intertwining moral ambiguity with explosive confrontations across a world teetering on revelation.