Spa Island arc

The Spa Island Arc is an anime-only filler arc that began airing on December 21, 2008. It takes place after the Thriller Bark arc, which means it is the first filler arc with Brook as a Straw Hat Pirate.

The mini-arc begins with the Straws Hats already on the titled island, an artifical place that houses many recreations the crew enjoy individually as explained by Doran, the owner of said island, to Nami and Robin. Meanwhile Luffy, Chopper, and Ussop goof around in the wading pools and water slides, attracting the attention of a young girl who enjoys their antics. She introduces herself as Lina and her pet sea raccoon that can shape shift (albeit always small in size). Lina also points out her sister Sayo whose busy looking over a notebook. Soon Nami, Sanji and Robin come over to meet the girls though they can't help but be curious of the notebook Sayo closely guards. Feeling a little uncomfortable, Sayo decides to leave the island with Lina and their pet in tow. Before they can though Foxy, along his loyal crewmates Porche and Hamburg, suddenly apper much to the SH's surprise (though Luffy takes awhile to remember who he is). While still miffed at his defeat since their last meeting, Foxy only concern is the sisters' notebook. To which he reveals a new mecha, a mirror covered image of his head which his crew quickly enter into and spin it. Foxy then aims his Noro Noro power out from under it causing the beam to reflect off the mirrors shoot everywhere. Both the SHs and the sisters are hit and slowed allowing Foxy to easily take the notebook from them. Foxy then snaps his fingers and the floor underneath the group is slide out from under them which will cause them to fall into the ocean once the 30 second time limit is up.

Franky and Brooke suddenly come into the area having just left the spas though wondering what the rest of the crew is doing floating in the air. As the Noro beam finally wears off, Luffy shouts for Franky to beat Foxy just and he and the others plunge toward the ocean. Franky obliges and blasts Foxy with his Weapons Left causing the residents on the island to panic and quickly flee the island. Meanwhile Luffy manages to save the sisters as well as himself while Robin catches the other falling cremmates. Foxy is angered that Luffy managed to make more crewmates since they last encounter and runs back to his mecha. However Hamburg closes the door on it too hard breaking the mirrors over it. Luffy then hits the bunch with his Boozuka move knocking them three into the ocean. After the commotion finally dies down, Nami eventually points out the notebook Sayo hold who finally decided to explain the sister's story. The two are the daughters of a scientist who believe he could make a genuine gem. However the village they live in found the idea foolish and would often ridicule the scientist, some of the village children even playing pranks on him like painting a gold horned beetle (which was said to bring misfortune to a village if it was found) and laughing as the scientist freaked out after finding it. Still he always laughed these off, looking on the bright side of everything as he loved the village dearly since its where his wife was born (who apparently died, she only shown in a photograph). Then one day their father headed off on a long expedition, leaving the sisters by themselves.

After about a year, their pet sea raccoon suddenly returned with the notebook containing their father's notes and a letter asking the sisters to finish his research, the scientist apparently having died. Lina however is bitter because she thinks her father abandoned Sayo and her, seeing no point in the research since they can't decipher the notebook. But Luffy thinks otherwise which Sayo gather up the courage to ask for the crew's help in the research but a trapdoor suddenly opens under her and she falls through. Unknowest to the group Doran had been eavesdropping on their conversation with his Den Den Mushis over the island and scheming to take treasure for himself, having been the one employed the Foxy Pirates and sic'd them on the sisters. The group panic over what to do until Luffy makes the suggestion to just simply destroy the island much to Doran's panic. The crew (which includes Zoro now who noticed the other island goers leaving) muddle over it but come to conclusion that its the best idea since they'll find Sayo faster that way. With that the crew proceed to the wreak the place, taking out the island's security that come after them in the process. Doran eventually stop the bunch showing them Sayo tied to a stake and a gigantic cannon aimed at her. To show he serious, he fires a warning shot that barely misses Sayo. Doran then demands the notebook for Sayo's life. Lina prepares to give it up but Sayo yells out not to. Explaining their father never abandoned them, on the day of Lina's birthday he wasn't able to come back home in time. After a few days passed he eventually returned with objects needed for his research. He noticed the cake however, realized his folly and ate it all resulting in a stomachache. When Sayo and he were alone, he explained his regret for not making it back in time and decided to dedicate his gem research to making one for Lina. The reason he never came and sent his notebook to the sisters was because the Foxy Pirates were tailing him and he didn't want to put his daughters in danger.

Upon realizing the truth, Lina has a change of heart and yells out her refusal to Doran to relinquish the notebook. The SH then proceed to hinder Doran and rescue Sayo. While Luffy with Lina and her pet with him, jumps into the air, goes Gear 3, and preform his Giganto Ax move splitting the island in half and sinking it (much to the annoyance of his crew since they have to jump the debris). However Luffy forget about his shrinkage side effect from using Gear 3 causing Lina and he to go plunging into the ocean. Luckily Sanji jumps in after them. As he pulls the two up, Lina notices an X-shape crack on the ocean floor leading to an underwater volcano. When she reaches the surface, she explains this find to the everyone. Sayo checks the notebook over and see it the x-mark they were looking for which was right under the spa island (and in effect under Doran's nose). The heat from the lava soon makes steam around the bunch and the reflection from the sun causes a rainbow effect. The sister then realize the steam being the final ingredient to make the gem. Doran and Foxy's crew see this phenomenon as well. Upon realizing that that was the treasure all along, Doran allows Foxy to "keep it" and swims away with Foxy's crew chasing him angry that they won't get any material treasure for their trouble.

A few days later, the SH's continue their journey when the sisters' pet sea raccoon flies in and delivers a letter to the crew from the two. They succeeded in making the rainbow gem and are living happily with their father who returns just in time to see the creation of the gem. What more the sisters sent the rainbow gem to the Straw Hats as thanks. The crew gather around to admire the jewel when it suddenly starts raining candy on them. In the midst of this, the gem gets knocked out of Luffy's hand prompting Nami to frantically order everyone to search for it on the deck. Episodes: 382-384