Chapter 900 is titled "Bad End Musical".
Big Mom eats the wedding cake, which she euphorically enjoys. The Big Mom Pirates rejoice as her cravings come to an end, and they quickly overwhelm their opponents as Oven drives away the Sun Pirates, the forces on Cacao Island gain bullets effective against the Vinsmoke Family, and the Thousand Sunny is attacked by the Queen Mama Chanter.
On and around Funwari Island, Perospero and Chiffon watch expectantly as Big Mom begins eating the wedding cake. Chiffon remembers being annoyed at Sanji's carefree confidence when they were making the cake, but now understands the cook's immense capability. Big Mom falls back after taking her first bites, which worries Perospero, but she begins shedding tears of utter delight as she loudly proclaims that this is the wedding cake she has been looking for. Everyone watches as Big Mom's mindless rampage comes to an end. Bavarois wonders about poison in the cake, and although Perospero still believes that there is, he figures that it was ineffective against Big Mom. As she tears into the cake, Perospero contacts all of Totto Land to announce the end of her rampage, causing everyone to cheer and celebrate. Pudding is given credit for the cake's creation, and as she hears citizens thanking her from an alley in Cacao Island, she smiles and reflects that she was not the one responsible.
On the sea near Cacao Island, Daifuku and Smoothie watch as the Sun Pirates halt the movement of the Big Mom Pirates' fleet and attack it, creating a path for the Straw Hats to sail through. Jinbe finds out that his former crew had also disabled the Territorial Sea Slugs. However, Oven steps out of a mirror onto one of the Cacao Island blockade ships, and reports to the ship's crew that Brûlée had brought his army bullets that are effective against Germa 66's forces. Stating that he cannot forgive Luffy for defeating Katakuri, Oven sticks his hands into the ocean and boils it. The heat reaches to where the Straw Hats and Sun Pirates are, forcing the Sun Pirates to retreat deep underwater to escape the scalding temperatures. On Whole Cake Island, Mont-d'Or receives a report that the Queen Mama Chanter has almost arrived.
As Big Mom continues eating the cake, she begins singing, looking for words to describe a cake whose deliciousness she can barely comprehend. At Cacao Island, the Queen Mama Chanter confronts the Thousand Sunny while the Vinsmokes are overwhelmed by the Big Mom Pirates' enhanced bullets. The cake gives Big Mom flashbacks to Mother Carmel and her sixth birthday party, and she realizes that what she is tasting now is the same as the croquembouche from that joyous day. She expresses a desire to partake in a meal with her childhood family again someday, and states the dream she got from Carmel of creating a utopia in Totto Land where all races could live in unity. As Big Mom fantasizes, her crew hits the Germa 66 fleet with a massive blast, and Snack and another person confront Judge. Further away, the Sunny is attacked by the Queen Mama Chanter's cannon fire, and the Straw Hats' ship is seemingly destroyed as the sail bearing its Jolly Roger is shown floating through the ocean-like wreckage.
- Big Mom eats the cake and enjoys it.
- Oven uses his Devil Fruit ability to make the ocean hot in order to defeat the Sun Pirates.
- The Vinsmokes are overwhelmed by Oven's army using reinforced bullets.
- The Thousand Sunny is intercepted and attacked by the Queen Mama Chanter.