Ruluka Island Arc

The Rainbow Mist Arc is a part of the Filler Arcs in the anime One Piece.

Like some other fillers, this arc starts off with the Going Merry being chased by a small fleet of Marine ships. Luffy and crew barely escape when the Marine's Major accidentally sinks one of his own ships. The crew then make their way towards an island that is ruled by a dictator, who is actually an old pirate, that is over-taxing the people in order to build the Rainbow Tower. The island also has a scientist who is reaserching something called the 'Rainbow Mist.' Eventually the Going Merry, with all but Sanji, Nami, and Chopper aboard, gets caught in the Rainbow Mist and discovers some children within. Eventually they all get out and it is shown that the children are actually the Marines from before.

This story arc is very interesting, because from the time that Nico Robin joined the crew, she has been seen reading books almost non-stop. These books have all been titled 'Rainbow Mist,' I through VIII, and are all about the story contained within this arc. Robin states that she got the books while in Alabasta.

This arc consists of episodes 139-143.