"A Vow Between Two Men - Luffy and Kozuki Momonosuke" is the 771st episode of the One Piece anime.
As everybody reacts to learning that Momonosuke's father Oden, who was executed, travelled to Laugh Tale on Gol D. Roger's ship, Robin realizes that Oden, must have known about the Void Century, which the archeologists of Ohara spent their lives studying. Zoro believes that this is the reason that Kin'emon's group of samurai were targeted by Doflamingo and Caesar, who have ties with Kaidou, even though Oden kept all the information to himself for the safety of his people.
Kin’emon, as well as all the other retainers, say they plan on fighting back because of Oden’s last words, which were, "Open up Wano Country!" The reason the samurai came to Zou is to ask their allies, the Minks, to help them fight and the rest of the samurai, excluding Momonosuke, ask Law and Luffy for their help. The rest of the Straw Hats accept the offer without any hesitation, but Luffy declines the request. As the group try to knock some sense into their captain, Luffy calls out the crying Momonosuke and says he should be requesting their aid if he is the supposed leader of Wano Country. Momonosuke steps up and pleads for Luffy’s help to take down Kaidou, as he is too small right now but still wants to protect all of his retainers. Luffy then accepts Momonosuke’s request and the rest of the leaders unite to form the Ninja-Pirate-Mink-Samurai Alliance, whose goal is to defeat the Emperor Kaidou.
Characters in Order of Appearance
- After Luffy's group learns that Oden was part of Roger's crew, we're then given a recap on the Void Century.
- The anime adds the following:
- Usopp asking the samurai if they knew the secret of the world after Zoro explained the reason why Doflamingo and Caesar were after them.
- After the samurai and the two rulers of Zou revealed Oden's will to open Wano Country to the world, Brook explains to Chopper how Wano Country is closed off from.
- Right after Inuarashi and Nekomamushi explain that they will use the true power of the minks the next time they face the Beasts Pirates, Chopper tells Nekomamushi to take his injuries more seriously.
- Kanjuro and Raizo also asking for Luffy's aid.
- Franky and Chopper also encouraging Luffy to ally with the samurai in their cause.
- After Kin'emon asks Luffy for his aid, the anime shows Luffy saying that he refuses more times than in the manga.
- When Nami tries to embrace Momonosuke in the manga, Brook angrily states that she shouldn't. In the anime, he doesn't say anything.
- Momonosuke's flashback to the day Kaidou sacked Wano Country is extended, showing a large blaze started by flaming arrows, Kin'emon's panicked reaction, Lord Oden calling out while trying to escape the flames, and the instant Momonosuke's mother was slain.
- When Momonosuke ran into Kaidou, Kaidou is shown in full and wielding his mace rather than a simple glimpse of his mouth.
- Kaidou's eyes are shown clearly during Momonosuke's flashback, staring down at him with hatred. In the manga, a clear view of Kaidou's eyes was first shown when he was venting his rage over losing his SMILEs.
- After Kin'emon comments on how Luffy treats Momonosuke like an adult, the manga showed Inuarashi saying how admirable it was. In the anime, it is Raizo instead.