Gimmy Adai is introduced as a young orphan boy from the subterranean village of Adai. Along with his twin sister, Darry, he is chosen to be sent to the surface when the village’s population exceeds its strict limit of fifty people. Because they have no parents, the village elder selects them for this exile, leading Rossiu Adai, the elder’s son who has cared for them, to decide to accompany them to the surface. This trio is discovered by Team Gurren, and Gimmy and Darry become lasting members of the group.

In terms of personality, Gimmy is established as the more impulsive, outgoing, and often reckless half of the twin pair. During the first part of the story, he is almost never seen without his usual joyful and energetic demeanor, providing a sense of childlike wonder and serving as a source of comic relief alongside his sister. He shares a very strong bond with Darry, and they are frequently left to their own devices. However, Gimmy also has a naive side; he initially believes that Simon, due to his immense Spiral Power, could bring people back from the dead and struggles to understand why Simon accepts the losses the team suffers. This childish perception fades as he matures.

Following a seven-year time skip, Gimmy has grown considerably, both physically and emotionally. His hair is now spiked up, though he retains a distinctive lock of hair between his eyes. He has matured into a more level-headed soldier and is deemed capable of piloting his own mecha. He and Darry become the only named pilots of the Grapearl squadron, with Gimmy piloting a custom blue model, a mass-produced mecha developed from research on Gurren Lagann, which has an arsenal including automatic handguns and blades. He takes his role as a commander of the Grapearl squadron seriously, protecting Kamina City from Mugann attacks alongside his sister.

Gimmy’s role expands as the conflict against the Anti-Spiral intensifies. He shows great emotion and is distraught over the losses of his friends, particularly Jorgun and Balinbow, who sacrifice themselves to save him and Darry. He is not immune to fear; when the Super Galaxy Dai-Gurren is trapped in ultra-dense space, he is struck by terror yet still desires to join the fight. One of his most critical moments comes when Simon, after Nia’s disappearance, entrusts Gimmy with Lagann’s Core Drill, finding him worthy to inherit it. In the epilogue, set twenty years later, Gimmy and Darry are seen not only as the commanders of the Grapearl squad but also as the new pilots of Gurren Lagann itself, continuing its legacy. His notable abilities include his skill as a pilot of the custom Grapearl and, later, the capacity to harness Spiral Power. On a smaller scale, Darry once saves Gimmy by shooting down missiles aimed at him, commenting on his perfect aim, which highlights his competence in combat.