Chapter 940 is titled "Sparks of Rebellion".
The Straw Hats learn more about Tonoyasu, who has no prior connections to the Kozuki Family but wishes to join the fight against Orochi. He was forced to sell his daughter, Toko, to the Flower Capital, but his kind actions to everyone in Ebisu Town have caused him to be considered a saint.
In the Prisoner Mine, Hyogoro teaches Luffy about advancing his Busoshoku Haki, and they are eventually left alone in the ring until morning while the Beasts Pirates retire for the night. Raizo and Caribou then arrive, and Hyogoro is encouraged upon reuniting with the former, saying that there are tens of thousands of prisoners who would ally themselves with the Kozuki Family. Meanwhile, Big Mom's group enters Udon.
A short time ago, Law had left Ebisu Town to rescue his crewmates, criticizing Shinobu for not trusting them and eroding their alliance. In the present, Usopp wonders why Shinobu decided to blame the Heart Pirates for exposing the alliance's secret messages, but Nami understands why she feels so strongly about it; both of them admit that they would expose the alliance quickly if captured. They then hear some men shouting in hostility nearby, and an old woman reveals that they are former Flower Capital citizens who were brought here yesterday. The first one, Bungo, committed arson every night and bribed the city officials to stay out of trouble. The second one, Bongo, is a former lumber dealer who profited from the arson by selling lumber to the people rebuilding their homes. The third one, Bingo, was a priest who performed funerals for those killed by the arson with a massively increased rate. However, they all fell in love with Komurasaki and were swindled by her. The old woman then claims that everything she just said was a lie, but Nami does not believe her and wonders who she is and how she knew Komurasaki. Usopp finally recognizes the trio from their attack on Komurasaki in the Flower Capital yesterday, and the woman states that although Tonoyasu has done his best to care for them, they continue causing nothing but trouble.
Inside a house, Tonoyasu remarks to Kanjuro, Shinobu, Sanji, Robin, and Franky how the secret message was effective in spreading the word of the Kozuki Family's return, but became too effective and led to the enemy understanding it. He asks them to tell Kin'emon that he will definitely be joining the final battle, and he says he will have a busy week up ahead of him, wondering what to do first. He then leaves, and the Straw Hats ask Kanjuro and Shinobu who he is. To their shock, they do not know, and did not want to be rude in questioning him if he was once someone of high ranking. Yasu goes around town checking on the citizens and their ailments, and giving them portions of food and water to consume. The old woman says that Yasu is able to earn more money thanks to selling his daughter Toko to the Flower Capital, and Toko gives him most of the money she earns. However, Yasu does not want to keep the money for himself, and so shares it around with the townspeople, causing him to be absolutely beloved by everyone.
In the Prisoner Mine, Hyogoro instructs Luffy about advancing his Busoshoku Haki, telling him to make all the Haki flow through his fist. Luffy punches Madilloman and many more Beasts Pirates out of the arena, but does not succeed in projecting Haki from his fist. Luffy and Hyo continue fighting until night falls, and the Beasts Pirates retire until morning and leave the two in the ring without food. Hyo asks Luffy why he wants to fight Kaido, and after knocking out the remaining guards with Haoshoku Haki, Luffy explains the existence of the Four Emperors and how he wants to defeat all of them to become the Pirate King like Roger. Hyogoro recognizes Roger's name due to the pirate coming to Wano Country over 20 years ago, and becomes even more surprised when Luffy mentions Kin'emon's name.
Caribou then creeps into the sumo ring, and Raizo appears from within him to explain the situation to Hyogoro. He reveals how his and Kin'emon's group was sent 20 years into the future, and Luffy is unhappy to see Caribou, getting mad at Raizo for accidentally stealing the keys to his handcuffs. Caribou pleads with Luffy to let him serve him, claiming to have changed his ways. Luffy accepts, which secretly scares Caribou even more. Hyogoro is ecstatic to hear the news of the Kozuki Family's return and offers to be of service, and Raizo tells Luffy about the old man's former status. Hyogoro reveals that there are four more sections of the Prisoner Mine that are each as big as the one they are in, and tens of thousands of prisoners are kept there overall. Most of them are imprisoned solely for rebellion against Orochi, with the old yakuza bosses being here among many others, and this place has served as a breeding ground for hatred and rebellion that the government does not see. Luffy plots to destroy the prison and gain all these allies, though Raizo warns it will not be that simple.
In the nearby wastelands, meanwhile, Big Mom and Chopper's group has arrived at Udon. Big Mom complains about her great hunger and drowsiness, and Chopper continues to be worried as Kiku is excited about their arrival.
- Law has left Ebisu Town to rescue his crewmates.
- The three men that Komurasaki swindled are revealed to be criminals who used bribery to get away with their crimes.
- Tonoyasu is revealed to be Toko's father.
- Luffy continues to train to produce the Busoshoku Haki shockwave, but is still not making any progress.
- Busoshoku Haki is known as "Ryuo" in Wano Country.
- The Sumo Inferno has been put on hold for the night.
- Luffy agrees to let Caribou help him.
- After reuniting with Raizo, Hyogoro decides to help gain more allies.
- A map of the prisoner mine is shown.
- Hyogoro reveals that there is a total of five prisons in Udon that are linked together. Furthermore, the majority of the prisoners are rebels including the heads of the five Yakuza families.
- Big Mom and Chopper's group arrive at Udon.