On Ruluka Island, some of the Straw Hats make enemies of the Mayor and his men, who have placed high taxes on everything. Robin, Usopp, and Luffy meet Professor Henzo, who's doing research on the island's rainbow mist. When some of the mist shows up, Henzo borrows the Going Merry to go explore it.

Henzo, his friends, and the others try to find a way out of the ship graveyard. Meanwhile, the Mayor and his men let the information about the Rainbow Mist slip to the remaining Straw Hats still on Ruluka.