After being defeated by Pekoms, Caribou starts to kidnap mermaids again until Jinbe subdues him. Jinbe then departs Fish-Man Island with him and takes him to the G-5 Marine base. After the Caribou Pirates attack the base, Caribou escapes and leaves his crew behind. During a storm, he ends up on an island where he is nursed back to health by a granny. He is also mistaken for a revolutionary named Gaburu. After reuniting with his crew again, Caribou assumes Gaburu's mantle and leads the citizens in a revolution against Scotch. After emerging victorious, however, Caribou is defeated and taken away by X Drake.
During another peaceful day at Mermaid Cove, a scream is heard as a shadowy figure chases after two others. Upon a closer look, the figure is revealed to be Caribou, who began another mermaid kidnapping spree using his swamp powers after recovering from his defeat at the hands of Pekoms. However, Jinbe arrives and easily defeats him with his Fish-Man Karate. He then chains the pirate up in a barrel and prepares to deliver him to the Marines on a coated boat, waving goodbye to the inhabitants while Caribou fumes at being defeated again. As they are traveling to the surface, Caribou's younger brother, Coribou suddenly arrives with the rest of the Caribou Pirates on a newly built Numabou to rescue his brother from Jimbe, making Caribou elated. However, Jinbe gets out and uses his swimming skills to quickly flee from them while hanging on the boat with Caribou still inside, much to the pirate's displeasure.
They then make it to the surface, right next to the dilapidated G-5 Marine base, where Jinbe drops the surprised Caribou off. Caribou was then found by the vicious marines of G-5 led by CommodoreYarisugi, who planned to torture the pirate in several grueling ways, ultimately deciding to burn him at the stake. Just then, the Caribou Pirates arrive to save their captain, with Caribou himself loudly demanding for them to hurry. The pirates begin fighting the marines, with Coribou dealing a blow on Yarisugi before chopping down the stake Caribou was on before he could start roasting over the fire, allowing him to escape. However, the ungrateful Caribou then takes the Numabou to escape alone, leaving Coribou and the rest of the crew at the mercy of the despicable G-5 Marines, who've managed to subdue them. At some point afterwards, the ship was wrecked in a storm, which Caribou believes is God's wrath for leaving his brother and men behind. He is forced to escape the sinking ship on a small row boat.
Caribou barely survives the storm and washes up on a winter-island with metal trees and rocks. After falling unconscious, he then wakes up to find himself in bed wearing new pajamas within the home of a sleeping old woman, who had apparently carried him inside and cared for him. Ever the evil pirate, Caribou gets out of bed without waking the woman and helps himself to her meat-pies and jewelry. The woman then wakes up and apparently forgives Caribou for trying to rob her, while also giving him a coat and a lunchbox full of meat-pies. She then directs him towards the island harbor, making Caribou very confused. On his way to the harbor, Caribou runs into some armed soldiers who bear the same symbol on Caribou's jacket. Upon seeing the pirate, they mistake him for someone-else named "Commander Gaburu", confusing Caribou. However, the old woman appears and chases the men away by pelting rocks at them. With the men gone, Caribou continues his way to the harbor while waving goodbye to the woman, who waves goodbye back.
Before getting there, Caribou decided to return to the town out of curiosity. While hiding and eating more meat pies, finds many soldiers of the same uniform searching for him in front of a large smoking building. Using his powers, he then investigates the building undetected and learns that it is a factory for manufacturing weapons, peeking his interest. Later on, he goes back outside and sees the soldiers calling out to the workers in the factory, exclaiming that the revolutionist, Commander Gaburu had returned, exciting the workers to take up arms in rebellion. They also show off a flag with the commanders' face on it, which is very similar to Caribou's face, making him realize that he had been mistaken for the revolutionist due to their similarities in appearance. Then suddenly, Kaidou's enforcer, Scotch appears and attacks the army and workers, scaring away Caribou. After defeating the revolutionaries, Scotch and his followers look down on them while burning their flag along with the entire town as a lesson of what happens to those who oppose them.
After retreating, Caribou returns to the old lady's house and is horrified to see her lying on the ground while her house was on fire. He then picks up a picture laying next to her and sees the real Gaburu eating a meat pie made by the old woman. The picture is titled "I love grandson Gaburu", revealing that Gaburu is the old woman's deceased grandson. The woman then wakes up and begs Caribou, who she apparently believes to be her grandson, to run away and not fight anymore. Suddenly, Scotch breaks into the house and ruthlessly attacks the old woman, shocking Caribou. The old woman gets back up and prepares to fight the cyborg all by herself to give Caribou an opportunity to escape, which he wastes no time in taking. Caribou continues to flee as the area behind him goes up in flames. He makes it to the harbor, and is surprised to find his old crew on a stolen Marine warship. He was initially afraid of their wrath for abandoning them before, but then Coribou runs up to give his brother a big hug and the others cheer on, showing that they all forgive him. Coribou explains that it was what their deceased grandmother would have wanted, since she always believed that brothers must always get along no matter what, making Caribou cry in regret of his heinous actions.
Meanwhile, Scotch captures Gaburu's grandmother and holds her up above the defeated revolutionaries, preparing to execute her as an example to those who defy him. However, he is stunned to see a Marine battleship come up to shore in front of him, carrying Caribou and his crew. Caribou decides to take up the deceased Gaburu's identity, with the rest of the crew acting as reinforcements, which surprises the old woman and the revolutionaries. While the crew holds off his subordinates, Caribou takes on Scotch himself, who attempts to riddle Caribou full of holes with his gun, but the bullets prove ineffective against the Logia user. Caribou then traps Scotch and his men in quicksand while also gleefully filling his mouth with mud, suffocating him. After defeating Scotch, Caribou then sinks the whole factory with his power, much to the joy of the workers, revolutionaries and Gaburu's grandmother. With his belly full, Caribou sits atop a large box and celebrates his act of heroism with his brother and everyone-else.
However, the celebration is cut short as a powerful dinosaur suddenly appears and attacks, injuring Caribou. The dinosaur is then revealed to be the Worst Generation member, X Drake, who is now another subordinate of Kaidou's. After defeating Caribou and the others, Drake then starts dragging away the commander back to Kaidou's base. Before he departs from the island, Gaburu's grandmother grants Caribou one final meat pie to take with him while his crew and the revolutionaries tearfully salute him. As he leaves on Drake's ship, Caribou bids farewell to everyone as they cry for him. Gaburu's grandmother also cries, but smiles as she recalls how Caribou defended her from Drake. She then visits the real Gaburu's grave, which has Caribou's wanted poster tacked on it, on a cliff while thanking Caribou for showing the same kindness as her grandson did, revealing that she knew all along that Gaburu was dead and that Caribou was an imposter, much to the shock of Coribou and the rest of the crew.