Episode 139

"Legend of the Rainbow Mist! Ruluka Island and the Old Man Henzo!" is the 139th episode of the One Piece anime.

Short Summary
On Ruluka, some of the Straw Hat Pirates 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.

Anime Notes

 * This is the first episode of the Rainbow Mist Arc
 * In the Funimation dub, this episode plays Nico Robin's theme tune during the break but shows Roronoa Zoro's picture.
 * Zoro already knew about his new bounty somehow.