Gai Daido begins his journey not as a pilot, but as a mechanic, a background that fundamentally shapes his approach to combat and his deep connection to the machines he would eventually operate. His profound understanding of the Getter Robo Go's mechanics, particularly his ability to assess a machine's condition through sound and vibration, is his defining skill, one that allows him to push the damaged robot to its utmost potential. This technical expertise is what led to his recruitment as the third pilot; during a sudden Metal Beast attack when the designated pilot was unavailable, Gai was called upon, and despite initial reluctance from the team's leader, he improvised a maneuver that allowed the damaged machines to form the Getter Gai configuration.

Physically, Gai is a large, muscular young man with a characteristic crew-cut of short black hair. His personality is marked by a deep, almost reverential affection for the Getter Robo, earning him the nickname Getter Lover from his colleagues for his meticulous care and respect for the machine. This gentleness towards his robot, however, belies a tough and resolute nature that surfaces when his friends are threatened. At the Alaska Base, he bravely confronted racist American soldiers who were tormenting the Japanese scientists, while still managing to form a positive rapport with another soldier named Jim.

In the story, Gai serves as the reliable anchor of the Getter Team, often mediating between the impulsiveness of his fellow pilot Go Ichimonji and the more calculated approach of Sho Tachibana. He officially joins the team after proving his worth in battle, retreating with them to Alaska where he continues to maintain and repair Getter Robo Go during the brutal conflict with the Metal Beasts. He participates in key battles, including a difficult fight against Shinichi Tachibana within a mobile fortress. Eventually, he returns to Japan with Go to continue the fight, where their path leads to the discovery of the Shin Getter Robo, a far more powerful and dangerous machine.

Gai's character undergoes a profound and tragic development, particularly in the manga continuity, where he is overwhelmed by the immense power of the Getter Rays while piloting the Shin Getter. The exposure causes him to lose his sanity, and he attempts to destroy the very robot he loved. During this act, he is absorbed into the mecha, assimilating into its core. In his final moments, he experiences visions within the Getter Rays, gaining a transcendent understanding of the mysterious energy. As he is fully absorbed, he communicates that he has become a part of the Getter entity itself, a haunting end for a character whose identity was so tied to the machine. His notable abilities revolve around his genius-level mechanical intuition, which allowed him to pilot the Getter Gai formation effectively, and his combat skills are demonstrated in the weapons of his machine, such as the Breast Beam, Harpoon Cannon, and Great Hammer.