Lone Island in a Distant Sea! The Legendary Lost Island

Tracking down the resting place sought by the dragon tests the whole crew, Nami included. Once the Straw Hat Pirates arrive at Lost Island, they come upon an aged temple whose wall paintings might reveal where the island actually sits. All the while, Eric follows them across the open water.

Following the crew's getaway, the Marines set out in pursuit, but Eric remains unbothered, convinced the pirates will guide him to the millennial dragons. He cuts off a Marine attempting to brief Commodore Nelson, wanting the dragonite for himself, yet Nelson catches the news regardless and, enraged, sends a fleet out toward Warship Island. The Straw Hats, meanwhile, tow Ryu along; when hot food slops onto the slumbering dragon's head, the shock jogs his memory, and he remembers that Lost Island lies to the east of Warship Island.

As the Going Merry nears a mirage, Luffy is pulled into his own reflection and the vessel vanishes from the watching Marines' view. A thick fog and an abrupt storm follow, tearing the ropes towing Ryu until Zoro grabs hold of them and Luffy drags the dragon to safety. Spotting an island sheltered within the storm's eye, Usopp alerts the crew, and Nami sets a course for it. They bring Ryu ashore and ascend the mountain in search of his nest, arriving at a building bearing a dragon emblem. Apis notices a hollow matching the shape of her pendant, but before the door opens the floor caves in, plunging them into a temple whose ceiling holds ancient murals that may point to the genuine Lost Island.

This installment is filler. Nami walks through the science of how mirages form, an understanding that proves useful once she later receives her Clima-Tact. The episode also debuts Luffy's anime-only move Gomu Gomu no Nagenawa.