"Tomica Kizuna Gattai Earth Granner" is a mecha anime series that centers around a group of children tasked with defending Earth from an alien threat. The story begins when the planet is invaded by the Zorndyke, a mysterious alien force that seeks to conquer Earth by deploying massive mechanical creatures known as Mecha Beasts. In response, humanity develops the Earth Granner, a powerful mecha formed by combining six smaller vehicles, each piloted by a child with a unique role. These children, known as the Earth Granner Team, are chosen for their courage, teamwork, and ability to harness the power of the Granner Stones, which are essential for operating the mecha.

The main characters include Haruto Shirogane, the team's leader and pilot of the red Granner vehicle; Akira Yamabuki, the hot-headed pilot of the blue vehicle; and Rikka Sakuragawa, the calm and analytical pilot of the yellow vehicle. Other members include Sota Mogami, the youngest and most energetic pilot of the green vehicle; Yuri Kanzaki, the skilled pilot of the pink vehicle; and Takuma Aoi, the stoic pilot of the black vehicle. Together, they must learn to work as a cohesive unit to unlock the full potential of Earth Granner and protect their world.

The narrative unfolds through episodic battles against the Zorndyke's Mecha Beasts, with each encounter testing the team's resolve and ability to adapt. As the series progresses, the children uncover more about the Zorndyke's motives and the origins of the Granner Stones, revealing deeper layers of the conflict. Themes of friendship, sacrifice, and perseverance are woven into the story as the team faces increasingly formidable foes and personal challenges. The series balances action-packed mecha battles with moments of character development, highlighting the growth of each team member as they confront their fears and insecurities.

The climax of the series involves a final confrontation with the Zorndyke's ultimate weapon, requiring the Earth Granner Team to push their limits and rely on their unbreakable bond to save Earth. The resolution ties together the overarching narrative, emphasizing the importance of unity and determination in the face of overwhelming odds. Throughout the series, the interplay between the characters and their evolving relationships serves as a driving force, making "Tomica Kizuna Gattai Earth Granner" a story that combines thrilling mecha action with heartfelt storytelling.