Gabu Samejima, a young man with striking red and pink hair and amber-brown eyes, dresses in a sleeveless dark red turtleneck layered under an orange jacket, paired with black shorts, gloves, elbow guards, and metallic shin-knee guards. At formal X-Zone ceremonies, he swaps this for a crisp white shirt and gray coat.

Commanding Team Shark Tooth from the saddle of his Idaten bike, Bloody Fang, Gabu wields unmatched mountain biking prowess alongside a brash, self-serving demeanor. Driven by ambition, he initially seeks dominance over X City, ruthlessly sidelining those he deems inferior. Beneath this hardened exterior lies a fiercely loyal core, though his guarded nature and sharp intellect keep his vulnerabilities tightly veiled.

Gabu orchestrates a high-stakes mountain bike race against rival Sho Yamato, exploiting the X-Zone to hone his team’s skills. After Sho’s group is thrust into the real X-Zone, Gabu seizes control of X City, ousting its mayor and deploying enforcers to thwart Sho’s progress. His relentless pursuit of power culminates in exiling his brother Taiga from Team Shark Tooth, leaving him destitute.

To secure dominance in the Idaten Tournament, Gabu kidnaps Kiku, sister of competitor Koei, manipulating him into sabotage. Defeated by Sho, Gabu retreats to his original world but later returns to rescue stranded ally Kyoichi Shido, forging a fragile alliance with Sho’s team against the enigmatic Team X. Captured during the clash, Gabu is freed by his rivals, leading to an uneasy truce where both teams share stewardship of the man-made X-Zone.

His journey traces a turbulent arc of authority, betrayal, and reluctant camaraderie, anchored by his role as Team Shark Tooth’s calculating leader and the gradual unraveling of his emotional armor.