The Zou Arc is the twenty-eighth story arc in the series and the third in the Pirate Alliance Saga of One Piece, continuing from the Dressrosa Arc. After defeating Doflamingo, the Straw Hats, Trafalgar Law, Kin'emon, and Kanjuro continue to Zou in order to reunite with Sanji and the others. Zou is the third island the Straw Hats encounter in the New World.
Jack left Zou leaving only some underlings behind, and Inuarashi had later realized that he went to rescue Doflamingo, effectively making the Straw Hats who defeated Doflamingo their saviors. The same day, Sanji's group arrived and encountered Sheepshead chasing Tristan. After disrupting Sheepshead's attack, the Straw Hats chased after Tristan, but she was scared and ran away from them. They came to the ruins of Kurau city, where they saw the tortured minks on the crucifixes. One of them, Pedro, begged them to save Inuarashi and Nekomamushi, as they had lethal wounds and could not be allowed to die.
Ceasar admitted that the gas, Koro, was his creation, and was forced by Sanji and Chopper to remove it from the air. Sanji defeated Sheepshead, who was attacking Nami's group, and the Beasts Pirates retreated. As the Curly Hats entered the city, they were attacked by Wanda, who believed them to be with Jack. Wanda was weakened by the poison, and was easily subdued by Nami, but held up a bomb to blow them all up. However, Tristan and Pedro revealed to Wanda that the pirates were not affiliated with Jack and helped drive the Beasts Pirates away. The pirates then went to work curing the Mink Tribe of the gas. In the present, Chopper prepared to go check on Nekomamushi and the Guardians. He and the Straw Hats were accompanied by Wanda and Carrot as they rode into the Whale Forest. During their ride, Zoro asked what happened to Sanji and Caesar, and Brook revealed that Sanji was possibly unable to ever return to them. When they fought the Big Mom Pirates, they accidentally gave away that they were going to Zou, and Pekoms knew where it was as he was a native of the island. The Big Mom Pirates arrived on Zou two days ago, and Pekoms and another crew member entered the island.