Little East Blue Arc

This non-canon, anime-exclusive run of four episodes exists chiefly to lead audiences into the feature film Strong World. It opens with a flashback to Shiki severing his own legs to break free of Impel Down two decades earlier, then jumps to the present. The arc holds the distinction of being the first such tie-in created to promote a movie, a pattern later repeated for Film Z, Film Gold, Stampede, and Film Red.

A submarine carrying the mariachi-themed Amigo Pirates, captained by the brothers Largo and Corto, receives an offer to join Shiki's growing assembly, provided they complete one task first. Meanwhile the Straw Hats, low on supplies, are attacked by a huge horned beetle that carries off several crewmates to a nearby island. There they meet Yoko, the beetle's owner, who calls the creature Boss and openly resents Luffy for being a pirate, since her Marine father died defending the village from raiders. The townsfolk, however, recognize the crew and lead them to a settlement built as a loving replica of the East Blue, complete with copies of each pirate's home.

The Amigos crash the celebratory banquet demanding Boss, who is a runaway from Shiki's hideout. When the villagers refuse, Zoro, Sanji, and Luffy beat down the henchmen, but Largo ambushes Luffy with a spiked net, revealing his power from the Ami Ami no Mi to forge nets from anything he consumes. After stringing up the captives, the brothers threaten to wipe out the town until Boss surrenders himself. Luffy tears free, and Boss undergoes a molt that burns away the nets, setting the stage for a final clash. Luffy chases Largo to the shore and, after the pirate turns his own body into a net, breaks loose and slams him into his submarine. With the Amigos captured, the crew sails on, while Shiki, told of the failure, brushes it off and declares the time has come to launch his scheme.

Because the story is filler designed purely as a prologue, it leaves no lasting mark on the canon timeline beyond delivering viewers to the Strong World film. Yoko softens her view of pirates after watching the Straw Hats protect both Boss and her village, and Luffy promises to return one day. The Amigo Pirates are locked into a cage Franky had originally fashioned for Boss, and Shiki's stated readiness to begin his plan points directly toward the events of the movie.