Gai serves as a mechanic within Benkei Kuruma's group after humanity retreats to underground shelters post-global catastrophe. His father, a Getter Robo mechanic, imparted foundational education in Getter Ray physics and mechanical maintenance, enabling Gai to conduct specialized upkeep on Getter machines and grasp their operational principles.

Initially a support mechanic, Gai transitions to combat after Benkei's injury during an Invader assault. He pilots Shin Getter-3 in the new Getter Team alongside Go and Kei Kuruma. His mechanical expertise aids piloting, letting him intuitively evaluate the Shin Getter's condition through auditory and vibrational cues. He also operates non-Getter vehicles like the Beetle T23 transport craft proficiently.

Physically, Gai has a large, muscular build with short black buzz-cut hair and typically wears a standard pilot suit. His personality blends gentleness and conflict aversion, though extreme stress sparks aggressive reactions. He exhibits deep loyalty to teammates, particularly protective concern for Kei, whom he quietly admires—sometimes manifesting as possessiveness. Childhood stories from his father instill profound respect for the original Getter Team.

Throughout conflicts against Invaders and Dr. Saotome's forces, Gai evolves from technical support to frontline combatant. His mechanical knowledge enables field adaptations during missions, including Manhattan and Pacific operations. His development focuses on applying technical skills in combat while navigating team dynamics, especially his protective stance toward Kei and reverence for legacy Getter pilots.