The episode opens with Usopp pretending he is in a great battle as captain of the Going Merry, fending off attacking pirates. As he is doing so, Luffy announces that he has finished the pirate flag for their ship, and holds it up. It's a terribly drawn skull and crossbones, of course. The others are horrified of the artwork, and so Usopp tells them that he is a great painter. He paints a pirate flag with his own face on it, but the others reject it so he paints a proper pirate flag, a very nice one at that. They fly it on the mast and continue to sail. As they are sailing, Nami spots an island in the distance with her telescope, saying it is Legendary Treasure Island. Usopp says how he heard that there is a valuable treasure on the island, but if one tries to claim it they will face God's wrath. As the Straw Hats draw nearer to the island, the weather turns foul and the waters very choppy. After a tough sail they make it to the island. The Straw Hats head into the jungle, looking for treasure. Zoro lies down and starts to nap, and as Usopp is shocked at how he can sleep in a creepy place like this, the Straw Hats find themselves surrounded by strange animals, creatures that are combinations of two or more animals. A voice booms through the jungle, claiming to be the Guardian God of the island and telling them to leave. Luffy picks up a lion pig that bites him on the face. The voice is shocked and Luffy explains he ate the Devil's Fruit. A gun then pokes out through a bush and shoots Luffy in the back, but Luffy bounces the bullet into the air with his Gomu Gomu powers. Luffy then spots a twitching green bush, and the owner of the voice takes off running. Luffy, Usopp, and Nami catch up to the man in the treasure chest, named Gaimon. Luffy explains to him how he wants to go to the Grand Line and claim One Piece, but Gaimon doesn't think he can do it. Luffy and Gaimon converse about how they can't read a map, and Nami is angered by this. Gaimon then explains how he became trapped in the treasure box as Zoro finally joins them. He explains that twenty years ago, he was with his crew in search of the treasure, and as they were leaving, he noticed how the captain never searched on top of a large cliff. Gaimon scaled the cliff but slipped and fell, getting stuck in a treasure box. He found that his crew had left, and he thought he would have the treasure on the ridge to himself, but found he could not climb in the box. When Luffy tries to pull Gaimon out of the box, he explains that his body grew to match the shape of the box, and his body will be ruined if the box is broken. Luffy then realizes that Gaimon uses the strange animals of the island to ward off visitors. Inspired by Gaimon's story, the Straw Hats decide to help Gaimon find the treasure. They come to the ridge and Luffy uses Gomu Gomu no Rocket to launch himself up to the top, where there are five treasure chests. He refuses to hand them over to Gaimon, and while this shocks and angers Nami and Usopp, Gaimon realizes that the treasure boxes must be empty. Luffy confirms this, and so Gaimon begins to cry, saying that he's been guarding nothing for twenty years. Luffy says it could be worse, as he could have died guarding nothing, and he offers Gaimon to join their crew. Gaimon decides to stay with the strange animals of the island, however, as he has decided to protect them instead of the treasure. With this adventure behind them, the Straw Hats set sail in the Going Merry once again, waving goodbye to Gaimon as the episode draws to a close.