Monkey D. Luffy captains a small three-person crew with Roronoa Zoro and Nami. Adrift in a dinghy and paralyzed by hunger, they are attacked by a plesiosaur. The monster destroys their boat, seizes Nami, and strands Luffy and Zoro, who wash ashore on an island enslaved by pirate Ganzack. Luffy utilizes his rubber abilities from the Gum-Gum Fruit, stretching his limbs for attacks like the Gum-Gum Pistol. Pirates trampling him forces seawater from his lungs, reviving him.

Driven relentlessly by hunger, Luffy resolves to take on Ganzack after learning the villagers lack food and hearing of provisions in Ganzack's fortress. He exhibits a carefree, impulsive nature, rushing headfirst into danger. Yet he displays fierce protectiveness over his straw hat, a treasure from his mentor Red-Haired Shanks. When Ganzack stomps on the hat, Luffy reacts with uncharacteristic rage, snarling a proud declaration of his identity as a pirate.

Early tension marks Luffy's interactions with his crew, especially pragmatic Nami after her temporary betrayal to Ganzack. Despite this, he trusts her upon her return and accepts his hat when she reveals her deception was a ruse for their freedom. He relies on Zoro in combat despite frequent bickering. Luffy bonds briefly with Medaka, a girl seeking her captive father. He protects her during the conflict, and she later presses a life preserver into his hands as thanks.

In combat, Luffy directly confronts Ganzack, prying open the pirate's crab-like armor and adapting to foam attacks. He defeats Ganzack with a Gum-Gum Hammer, punching the villain skyward where he collides with an exploding cannonball. After liberating the island, Luffy departs with his crew on a new boat supplied by grateful villagers, resuming his journey toward the Grand Line.