Chapter 839 is titled "I Owe You My Life".
Luffy paints Kankichi Ryotsu's signature eyebrows on a giant wanted poster of the character as he and the Straw Hats commemorate the ending of the manga Kochira Katsushika-ku Kameari Kōen-mae Hashutsujo.
The number on the poster in the cover upside down is "110596", while Kanchiki Ryotsu's eyebrows that Luffy is drawing resemble the number "3". "110" is the police phone number in Japan, while "5963" can be read as "ご苦労さん", which means "Thank you for your hard work", so Oda is saying "Thank you for your hard work, policeman" as part of his tribute.
The reunited Vinsmoke Family have breakfast in their castle. As they discuss their political affairs, Sanji and Niji engage in a confrontation which ends with Niji attacking the head chef, Cosette, and with Sanji once again denouncing his family's pride and values. Judge proceeds to threaten Zeff to pressure Sanji into cooperating with the upcoming wedding, leading Sanji to recall periods of his time at the Baratie.
Later, Sanji discovers a bloodied and beaten Cosette in the castle. Yonji appears and goads Sanji into confronting Niji again. Yonji then leads him to a sequestered area of the castle, where Sanji is shocked to discover soldiers of Germa 66 being monitored inside liquid capsules.
As the newly reunited Vinsmoke Family eat breakfast within the throne room of their castle, Judge reflects that Broc Coli Island was one of numerous nations impacted by the fall of Doflamingo's weapon trade; he and Reiju note that one side caved in and hired Germa 66 out of desperation to end the war, rather than continue sustaining casualties. However, Ichiji and Niji express complete indifference to the politics of the war, showing concern only for the money they had made. Yonji reflected on the profit-boosting possibility of working for both sides, but Judge says that it would make them no better than pirates. Niji then mentions the upcoming Reverie, and Judge replies that as their goal nears completion, the World Government will likely strip the Vinsmokes of their right to participate in Reverie.
Niji remarks that it is strange to see his father in high spirits, expressing surprise that Sanji ultimately proved of use to them. He tells Sanji that when Sanji left the family 13 years ago, the brothers often pondered humorous ways in which he might have died, causing Yonji to laugh. Sanji's only response is to tell Niji to finish the food left on his plate, but Niji replies that it was unappetizing and that he will throw it away. Sanji's expression darkens as he orders Niji to eat it, calling him a spoiled prince who does not know the value of food. This enrages Niji, who calls for the head chef Cosette; Cosette appears and vehemently apologizes for making food not to Niji's liking, and Niji tells her to stay still as he throws his plate directly at her. Sanji catches the plate before it makes contact with Cosette, causing the food to fall onto the floor. Both Niji and Sanji are angered, with the latter expressing fury over the former's attempt to harm a woman. Niji replies that she is just a menial servant, but Sanji picks up the food, examining it and complimenting its nutritional value. Cosette attempts to stop him so that she can clean it up herself, but Sanji remarks that she must have put in great effort to make the dish and he eats it off the floor, shocking Cosette. All the Vinsmokes (except Reiju) are repulsed by Sanji's action, but Sanji continues by telling Cosette that she used the perfect seasoning for this dish, causing her to become flustered and start crying from an earnest compliment by one of the royal family.
An enraged Niji attempts to kick Sanji, but Judge tells him not to attack Sanji before the wedding. Niji halts his kick right in front of Sanji's face, although the force of it is sufficient to knock Cosette over. Niji labels Sanji a shame to their family, but Sanji replies that being in this family was shameful to him. Sanji proceeds to berate them for not appreciating meals, harming women, and treating their subordinates like expendable pawns. Ichiji then interjects, saying that Sanji's comments only show that he had too long associating with commoners, and that they are meant to act like royals. Judge concurs with Ichiji and Niji and holds up a photograph of Zeff, wondering if he was responsible for Sanji's negative upbringing. Sanji is shocked that his father knows about Zeff, and Judge states that they have pinpointed the Baratie's location. Judge recalls receiving both the exploding wristlets and Zeff's photograph from Tamago, before telling his son that if he continues challenging and defying him, he will see to it that Zeff is killed. Judge tells Sanji that this is his first and final warning, before telling Sanji that he will leave his old friends and old life behind if he wanted everyone to remain unscathed. As his siblings leave the throne room, Sanji recalls being raised by Zeff on the Baratie as well as their tearful goodbye, and Judge instructs him to prepare to head to Whole Cake Island for their lunch meeting with Big Mom and Pudding later in the day.
Later, Sanji stumbles upon a heavily beaten and unconscious Cosette, becoming enraged at Niji for his possible vindictive actions. Yonji appears and states that Sanji brought this upon himself and Cosette by sticking up for her. Yonji asks if Sanji wants to confront Niji and Sanji accepts his offer, but they instead end up before a highly secured room; Yonji reminds Sanji that it was the same room they had never been allowed to enter as children. They enter the room, and Sanji expresses his disbelief as he sees dozens of soldiers from Germa 66 being kept in large bottle-shaped containers.
- Judge states that the World Government will likely deprive the Vinsmoke Family of the right to attend Reverie when they discover Germa's alliance with Big Mom.
- Judge threatens to have Zeff killed if Sanji does not obey him.
- Tamago was the one who approached Judge with the idea to use explosive cuffs and Sanji's connection to Zeff against him.
- Yonji leads Sanji to a room containing Germa 66 soldiers in large capsules while being monitored by scientists in the depths of the Germa castle.