After the cataclysmic battle on the volcanic island, where the Straw Hat Pirates witness the clash between Gojo and Zephyr, the Thousand Sunny crew sets sail once more, their hearts heavy but their determination unwavering. The battle against Zephyr, a former Marine admiral turned leader of the Neo Marines, marked a turning point. His Dyna Stones, capable of destroying entire islands, pose an unprecedented threat to the New World. Even though Gojo inflicted a crushing defeat on Zephyr, the crew knows that the former admiral will not give up so easily.
Luffy, true to his dream of becoming the Pirate King, declares to his crew that they must continue their quest, no matter the obstacles. On the Sunny's deck, the atmosphere is tense. Nami, bent over her maps, recalculates their route, while Usopp, still shaken by the power of the Dyna Stones, mutters about staying away from trouble. Zoro, sharpening his swords, wears a smirk, ready for the next challenge. Sanji, lighting a cigarette, appears distracted, Gojo's words about his sister Reiju echoing in his mind. Robin, as always, observes in silence, analyzing the implications of recent events. Franky, checking the Sunny's systems, cracks a joke to lighten the mood, but even he knows that the New World will offer them no respite.
Their next destination, guided by the Log Pose, is Punk Hazard Island, a strange place where the climate is split between freezing cold and volcanic heat. Upon their arrival, they discover a devastated island, marked by an ancient war between the admirals Aokiji and Akainu. The crew is quickly confronted by Caesar Clown, a deranged scientist working on macabre experiments. Caesar, with his Gas Gas Fruit, produces SAD, a substance essential for creating artificial Devil Fruits, the Smiles, used by Emperor Kaido to strengthen his army.
Luffy, following his instincts, decides to intervene upon discovering kidnapped children, victims of Caesar's experiments. However, the crew encounters an unexpected ally: Trafalgar Law, captain of the Heart Pirates and one of the Seven Warlords. Law, with his Operation Fruit powers, proposes a strategic alliance to Luffy to dismantle Caesar's network, which is under the protection of Donquixote Doflamingo, another Warlord and key figure in the New World. Luffy, without hesitation, accepts, sealing an alliance that will disrupt the balance of power in the pirate world.
At Punk Hazard, battles unfold. Zoro faces off against Caesar's henchmen, his blades cutting through hordes of enemies. Sanji, with his fiery kicks, protects Nami and Chopper, who are trying to save the children. Robin uses her Flower Fruit powers to neutralize the island's traps, while Usopp, despite his fear, deploys his new ammunition to counter Caesar's toxic gases. Franky, at the helm of the General Franky, destroys the laboratory defenses. Luffy and Law, on the other hand, directly confront Caesar. After an intense battle, where Luffy unleashes his Gear Third and Law utilizes his surgical techniques, Caesar is defeated and his laboratory is destroyed.
However, the victory reveals a darker truth: Doflamingo, manipulated in the shadows, pulls the strings of the SAD trafficking for Kaido. Law, determined to avenge Doflamingo for personal reasons, convinces Luffy to continue their alliance to Dressrosa, the kingdom where Doflamingo reigns as a tyrant. Luffy, outraged by the injustices caused by Doflamingo, accepts, motivated by his innate sense of justice and his desire to protect the innocent.
Before leaving Punk Hazard, the crew receives a desperate call from Kin'emon, a samurai from Wano, searching for his son Momonosuke, transformed into a dragon by a defective Smile. This encounter marks the beginning of a connection with Wano, an isolated nation under Kaido's rule. Luffy promises to help Kin'emon, reinforcing the idea that their battle against the Emperors is inevitable.
The Thousand Sunny arrives at Dressrosa, a vibrant island but marked by oppression. Doflamingo, with his String-String Fruit power, controls the kingdom like a puppet, manipulating the citizens and turning his enemies into toys through Sugar's Toy Toy Fruit, one of his subordinates. Luffy, Law, and part of the crew infiltrate the island, while Sanji, Nami, Chopper, Brook, and Momonosuke remain aboard the Sunny, soon attacked by Doflamingo's and Big Mom's forces, sent for still mysterious reasons.
In Dressrosa, Luffy discovers the horror of Doflamingo's reign: enslaved citizens, broken families, and a people manipulated by propaganda. He meets Rebecca, a gladiator from the Corrida Colosseum, and Kyros, a legendary hero turned into a toy. Their story, linked to the tragedy of Dressrosa's royal family, touches Luffy, who vows to free the island. Meanwhile, Zoro faces off against Pica, a stone giant, in a duel of brute strength, while Robin and Usopp ally with an army of dwarves, the Tontattas, to neutralize Sugar.
Law, consumed by his vendetta against Doflamingo, reveals his past: he is a survivor of Flevance, a town destroyed by the greed of the Celestial Dragons, and Doflamingo is responsible for his mentor Corazon's death. However, Law is captured, and Luffy must confront Doflamingo alone. The Warlord, with his powerful Haki and sharp strings, initially dominates the fight. Pushed to his limits, Luffy unveils his Gear Fourth for the first time, a spectacular transformation that boosts his speed, strength, and elasticity. In an epic battle, supported by the people of Dressrosa and his allies, Luffy triumphs with his King Kong Gun, shattering Doflamingo's string cage and freeing the island.
The victory is bittersweet. Law, though avenged, carries the weight of his past. The revelations about the Celestial Dragons and their corruption shock Robin, who sees parallels with her research on the Void Century. Luffy, exhausted but smiling, earns the respect of the citizens and gladiators, who swear to follow him. This victory propels Luffy as a major figure in the New World, his bounty rising to 500 million berries, attracting the attention of Emperors Kaido and Big Mom.
Meanwhile, Sanji faces a personal crisis. In Dressrosa, he learns that his family, the Vinsmoke, a dynasty of assassins from Germa 66, has arranged a political marriage with Pudding, a daughter of Big Mom. This news, tied to his painful past, deeply troubles him. When the Sunny is attacked by Big Mom's men, Sanji is forced to leave with them to protect his crew, leaving a note promising to return. This separation marks an emotional turning point for the Straw Hat Pirates, who vow to find him.
Inspired by the events in Dressrosa, Zoro intensifies his training, determined to surpass his limits to face Kaido. Nami perfects her weather techniques, while Chopper deepens his medical knowledge to treat severe injuries. Robin, intrigued by the Poneglyph clues discovered in Dressrosa, redoubles her efforts to decipher the secrets of the One Piece. Usopp, emboldened by his role in Sugar's downfall, gains confidence, and Franky plans upgrades for the Sunny. Brook, true to his humor, composes a new song to immortalize their exploits.
The events in Dressrosa have global repercussions. Doflamingo's downfall disrupts the Smile trafficking, weakening Kaido, who vows revenge. Big Mom, furious at Luffy's interference in her plans, prepares a counterattack. The Marines, overwhelmed by Luffy's rise, bolster their efforts to capture emerging pirates. The Celestial Dragons, humiliated by the revelations of Dressrosa, tighten their grip on the World Government.
As the Thousand Sunny sails towards Zou, a mysterious island inhabited by the Minks, the crew knows that the challenges ahead will be colossal. Kaido, with his army of artificial Zoans, and Big Mom, with her Totto Land empire, stand as walls in their path. Yet, Luffy, adjusting his straw hat, laughs at the horizon. "We'll beat them all!" he declares, his contagious optimism rallying his nakama. The journey to the One Piece intensifies, each battle bringing them closer to the ultimate treasure and the truth about the world.