The straw hats arrive on Zou, an island located on the back of the giant elephant Zunesha. The island is home to the Mink Tribe, a race of humanoid animals, who are caught in the conflict between the pirate crews and the powerful Yonko. The Straw Hats meet Raizo, a ninja and ally of the Kozuki clan, who reveals the significance of Zou in the larger story involving Wano Country.

During their time on Zou, the crew learns about the turmoil caused by the Yonko, particularly Big Mom, who seeks to acquire a powerful artifact known as the Poneglyph. The arc delves into the tragic backstory of the Mink Tribe, revealing their struggle against the pirate Jack and the alliance formed with the Kozuki clan. The crew also gains important information about the Red Poneglyphs, which are crucial for finding the One Piece.

Following the events on Zou, the focus shifts to Whole Cake Island, where the Straw Hats aim to rescue Sanji, who has been coerced into an arranged marriage with Charlotte Pudding, a daughter of Big Mom. The crew faces various challenges as they navigate the whimsical yet dangerous world ruled by Big Mom and her powerful family, the Big Mom Pirates.

The arc highlights Sanji's backstory, revealing his troubled relationship with his family, the Vinsmoke family, and the expectations placed upon him as a member of the Germa Kingdom. As Luffy and his crew confront Big Mom's formidable children, including the powerful Katakuri, they engage in intense battles that test their strength and resolve.

A significant part of the saga centers around Luffy's struggle against Katakuri, leading to personal growth and mastery of Haki. The saga culminates in high-stakes confrontations, with the Straw Hats orchestrating a daring escape from Whole Cake Island. With the help of unexpected allies, they manage to rescue Sanji and evade Big Mom’s wrath.

The saga concludes with the Straw Hats escaping Whole Cake Island, solidifying their bonds and setting the stage for future adventures. The events on Zou and Whole Cake Island deepen the story, revealing crucial information about the Yonko, the Poneglyphs, and the ongoing power struggles in the world of One Piece.