A Vow Between Two Men - Luffy and Kouzuki Momonosuke

As everyone absorbs that the executed Oden once reached Laugh Tale aboard Roger's ship, Robin deduces he must have grasped the Void Century, the very mystery the scholars of Ohara died pursuing. Zoro reasons this is why Doflamingo and Caesar, both linked to Kaidou, hunted Kin'emon's samurai, even though Oden guarded the knowledge to keep his people safe.

Driven by Oden's final words to open Wano, the retainers commit to striking back. They ask their mink allies and the pirates for help, and most agree, though Luffy at first turns the request down.

The samurai had originally come to Zou seeking the minks' aid, and now they appeal to Law and Luffy as well. The rest of the Straw Hats accept without hesitation, but Luffy holds out, pointing to the weeping Momonosuke and insisting the boy should make the plea himself if he truly leads Wano. Steeling himself, Momonosuke asks Luffy to bring down Kaidou, admitting he is too small to protect his retainers alone. Luffy agrees, and the leaders unite as the Ninja-Pirate-Mink-Samurai Alliance, sworn to topple the Emperor Kaidou.

The broadcast recaps the Void Century after the crew learns of Oden's place on Roger's crew. Anime-added beats include Usopp asking whether the samurai knew the world's secret, Brook explaining Wano's isolation to Chopper, and Kanjuro and Raizo joining the appeal to Luffy. Luffy refuses more times than in the manga. Momonosuke's flashback to Kaidou's assault is lengthened, depicting the fire from flaming arrows, Oden caught in the blaze, and the death of Momonosuke's mother, with Kaidou shown in full and his hateful eyes made plain. The episode belongs to the Zou Arc.