Chapter 811 is titled "Roko".
Color Spread: Docking Mini Merry II on a snowy pier, Luffy, Zoro, Nami, Usopp and several monkeys, all in winter wear, return from shopping with a large Doskoi Panda laundry bag and several grocery bags and meet Chopper and Sanji while drinking a can of "LADY COFFEE" outside.
Ten days ago, Sanji's group forces Caesar Clown to neutralize his poisonous gas, defeating Jack's subordinates and driving them off Zou. They tend to the wounded minks, saving their lives and earning their gratitude.
Back to the present, the Straw Hats, Wanda, and Carrot head to Nekomamushi, while the group discusses what has happened to Sanji and Caesar. Sanji has departed from Zou, leaving only a note behind. However, he may not be able to return, since Zou is a phantom island that is constantly moving. Brook then reveals the reason why Sanji left. Just two days ago, a more serious event took place after Jack attacked: the Big Mom Pirates caught wind of their crew's trail and followed them to Zou, of which Pekoms is a native.
Ten days ago, the Curly Hat Pirates wandered through the gas-covered terrain of Zou. Caesar Clown chuckled with delight at how powerful the gas was, revealing that it was called Koro and that he invented it. This caused Chopper to beat Caesar up, and the scientist cried that he did not fire the weapon, but Chopper said that no one would have suffered if Koro wasn't invented. Caesar attempted to deter them from rescuing the minks, saying that the species was strong and hated humans. The Eruption Rain then occurred, and Sanji, Chopper, and Caesar pulled themselves onto a branch. Suddenly, Sanji heard Nami screaming, and ordered Caesar to clear away the gas as he went to rescue her. As Sanji defeated Sheepshead and the Beasts Pirates retreated, a saddened Caesar used Roko to purge the Koro from the air.
Chopper went to Kurau City and noted that Caesar's solution was working as he called his crewmates over. The Curly Hats saw the fallen Mink warriors and were shocked, but also guessed that there were more, and Sanji wondered if Caesar was right about the Minks being violent. Suddenly, Wanda attacked Nami as she questioned whether the pirates were allied with Jack. Sanji and Brook raced to help Nami, but Nami said she was fine as the poison had weakened Wanda. Nami slammed Wanda into the ground, but the mink suddenly held up a bomb, saying she would blow all of them up. An angered Wanda asked Nami what grudge they held against the Mink Tribe and why they were intent on slaughtering everyone. Suddenly, Tristan came and told Wanda that the Beasts Pirates had retreated and that she had been saved by the Curly Hats. Pedro then revealed that they were not affiliated with Jack and that they had purged the gas from the air. Suddenly, Chopper came and shouted at everyone that the gas would become impossible to treat after 48 hours and ordered the minks to round up everyone who is capable of assisting him. Wanda teared up as she realized that the Straw Hats were going to save them, and Nami told her that not a single mink would be abandoned.
The Curly Hats eventually succeeded in treating all the minks, and the mood progressively improved as more and more people were healed. In the present, Wanda concludes her story as she licks Nami in thanks for her crew's work. Luffy expresses his anger at Jack and says that he would like to beat the pirate up, and Wanda reiterates that she doubts Jack is dead after seeing him fight. Chopper then tells his crew that he is headed to Nekomamushi and the Guardians so he can check up on them, and the Straw Hats and Wanda come along with him. Wanda reveals that she is active at all hours of the day as a ruler's aide and Luffy and Brook get excited about meeting Nekomamushi. They ride out into the night along with Carrot, and Wanda expresses relief that the full moon was covered by clouds.
Zoro asks Wanda what happened to Sanji and Caesar, as they still did not know that part. However, Brook tells him that most of the minks were not told what happened so they wouldn't worry. Brook says that the event happened only two days ago and told his crewmates that it was very possible that Sanji would not be able to return to them. Even though Zou was a Phantom Island that Log Poses did not point to, the Sunny crew made a grave oversight when they escaped from the Big Mom Pirates. However, the Yonko's crew overheard their destination, and one of their members, Pekoms, was a native of the island. And so, the Big Mom Pirates arrived at Zou, as Pekoms and another crew member prepare to go onto the island. Pekoms speaks to his captain over a Den Den Mushi and tells her to leave this to him, because Zou is his homeland.
- The name of the weapon Jack used is revealed to be "Koro".
- The flashbacks catch up to the events shown in Chapter 795, including Sanji and Chopper threatening Caesar, the eruption rain and the flood, Nami screaming, Sheepshead's attack and defeat, Jack's subordinates retreating, and Tristan watching the Straw Hats from behind a tree.
- The Straw Hat Pirates leave Right Belly Forest and head back to the Whale Forest to visit Nekomamushi and the Guardians.
- Sanji's disappearance is revealed to also involve Caesar's disappearance from Zou as well.
- Wanda and Carrot are revealed to be ruler's aides, minks that serve both Nekomamushi and Inuarashi during the day and night on Zou.
- It is revealed that the Big Mom Pirates arrived at Zou two days ago.
- Pekoms is confirmed to be one of the minks and to be from Zou.
- Pekoms suggests that only he and another crew member are enough to go after the Straw Hat Pirates.