Daichi Haruka, a spirited young boy, journeys to the moon during summer vacation and crosses paths with V-Mei, an elderly witch of the endangered Long-Ears race, and her granddaughter Guri Guri. Their homeland, Rabiluna, faces existential threats from the Jadou Clan, a ruthless faction pursuing universal domination. V-Mei recognizes Daichi’s latent Madou Force—a mystical energy marking him as a chosen Madou Warrior. This power allows him to summon and command Granzort, a towering robotic entity embodying Earth’s elemental strength, positioning him as a pivotal defender against the Jadou invasion.

Naturally curious and bold, Daichi evolves into a resolute leader who consistently places others’ safety above his own. He coordinates strategies alongside fellow Madou Warriors: Gus Yamamoto, who harnesses the wind-elemental Winzart, and Rabi, master of the water-based Aquabeat. His growth is marked by confronting vulnerabilities, including a deep-seated fear of carrots, which he methodically overcomes by the story’s end.

A skilled inventor, Daichi crafts a rocket-powered jet-board to swiftly reach Granzort during combat. Though occasionally bested by Jadou forces—forcing tactical retreats to the moon—he repeatedly rallies, showcasing tenacity and adaptability. His resilience underscores his progression from an adventurous child to a disciplined tactician.

The narrative touches on familial bonds through brief interactions with his mother, referenced in a related series. While the primary arc concludes with Daichi’s return to Earth, subsequent OVAs and spin-offs maintain his role as a steadfast guardian of both Rabiluna and his home planet, without expanding his personal journey beyond this established legacy.