GB began life as a cherished pet dog until his owner's suicide abandoned him. Fleeing after the ambulance carrying his owner, he became lost in the city and nearly died under a truck; Smith saved him, losing his front left leg in the process. Grateful, GB called Smith "Uncle Smith." Homeless, GB joined Nero's pack as a runner. A traumatic event occurred when he found abandoned puppies and brought them to Nero, only for Hougen, leader of the Southern Alps, to order their execution, suspecting Nero hid females. That failure etched deep into GB, cementing his self-image as a coward.

Meeting a nameless puppy hunting birds for his ill mother Sakura proved pivotal. After Sakura's death, GB vowed to protect the puppy and lead him to the Ohu mountains. He named the puppy "Weed," symbolizing resilience and the idea he would never be alone. This act established GB as Weed's guardian. During their journey, GB's cowardice resurfaced, like fleeing when Weed helped an ailing Golden Retriever named Lenny, yet he also showed fierce loyalty and flashes of courage.

GB evolved through numerous conflicts. In the Monkey arc, he joined Weed, Sasuke, and Kyoushiro to investigate disturbances, later recruiting allies like Buruge to fight the baboon Shougun. During the Russian arc, he concentrated on gathering allies and convincing Weed to rescue Gin's pack from Viktor in Hokkaido. His journey from cowardice culminated in the Hybrid arc. Following Weed to protect Koyuki and Kotetsu, GB confronted giant bears. The Third Hybrid's claws raked his body. Ordered to recover, he repeatedly tried to rejoin the fight. Seeing Weed in mortal danger, GB summoned his last strength to charge the bear, tearing off one of its claws before fatal wounds from the counterattack claimed him. Dying in Weed's arms, he asked for a hug, confessed his fear of death, and thanked Weed for their companionship. Weed buried him at the battle site. The Ohu army mourned at his grave before leaving; Sasuke stayed briefly longer.

GB's legacy continued in *Ginga: The Last Wars*. His spirit appeared to Sasuke, paralyzed by fear fighting Monsoon's kin. GB reminded Sasuke of his own bravery against the Hybrid Bear, urging him to find courage. This spurred Sasuke to protect Kyoushiro, though he suffered severe injuries.

Throughout his life, GB remained pessimistic and cynical, doubting himself and others, including humans. Despite this, he occasionally showed optimism and belief in hope. His loyalty to Weed evolved from protective worry to deep respect as Weed matured. GB held profound respect for Smith and carried enduring guilt over Smith's death. His relationship with Sasuke involved constant bickering and mutual reliance; GB sometimes reverted to cowardice but ultimately displayed fierce protectiveness, defending Sasuke from Hougen's henchmen.