Summary:
Luffy and the others sail near an uninhabited island and Luffy insists that they find someone there. After discovering an island full of unusual hybrid animals, they are confronted by the island’s guardian. Luffy and Nami discover that the island is actually inhabited by a strange man trapped in a chest, Gaimon. He learns that Gaimon has stayed on the island for twenty years to retrieve some treasure, but he can’t get to it in a trap. Luffy offers to help, but when he gets to the treasure, he finds that it was all taken before Gaimon even landed on the island. Gaimon was upset when he heard this, but Luffy’s positive attitude helps Gaimon overcome his depression. Gaimon decides to stay on the island and protect the animals rather than join Luffy’s crew, and the young pirates leave for another island.
Nami repairs Luffy’s straw hat after Buggy damaged it earlier, much to his delight. Despite her warnings, he shoves a hole in the hat, causing Nami to stab him in the forehead with her sewing needle. Zoro wakes up to the noise and starts asking for food. Nami spots an island in the distance and Luffy steers the ship towards the island as fast as possible in hopes of food.
The crew lands to find the island deserted and covered in forest. Luffy calls Zoro, but since he’s asleep, he and Nami go exploring without him. They find a dog/chicken hybrid creature, then a snake/rabbit and a pig/lion. Suddenly, a voice warns them to leave before the island’s curse hits them and they die. Nami and Luffy call the bluff guard and Luffy is shot by a bullet. After deflecting the bullet with his Devil Fruit ability, Luffy and Nami follow the direction of the shot and find a strange chest-like object with hair on top.
When they examine it, the strange object moves and runs away, but trips and falls over, revealing the person inside. Gaimon introduces himself and reveals that he’s been stuck in a treasure chest for 20 years and hasn’t spoken to another human being in all that time. Luffy tries to pull Gaimon out, but Gaimon claims that his body will disintegrate if he leaves the chest as it has formed over the years. Gaimon explains that he used to be a pirate and is happy to meet other pirates. While Luffy and Gaimon are talking, the Great Line is mentioned and they show Gaimon the map they have. Unfortunately, Gaimon has no specific knowledge and cannot tell them where the Grand Line is.
Nami interrupts them and explains the Grand Line. The world is divided into two parts, with one continent separating each part – the red line. The Grand Line further divides the world, dividing it into four seas and the Grand Line itself. The only one to conquer the Grand Line was Gold Roger. Gaimon states that the Great Line is known as a “pirate graveyard” and that although he has seen pirates returning from this area of the sea, they were changed men who had lost the will to live.
Gaimon goes on to explain the legend of One Piece; in over twenty years, not a single person has found the treasure that Gold Roger left at the end of the Great Line. After hearing that it might not even be real, Nami has doubts about Luffy’s goal. Gaimon tells the pair that he can’t leave until his mind is at ease about something.
Twenty years ago, Gaimon came to the island to find treasure with a pirate crew, but he could not find the treasure anywhere. Gaimon, determined that there is treasure, goes on a search. He finds the hill the crew looked around for, but not at the top. He climbs the hill and finds treasure chests at the top. Amazed that he actually found the treasure, he falls down the hill into the empty chest his crew found earlier and falls unconscious. After he wakes up, stuck in a chest, he finds that the crew has sailed away without him. Realizing that he is now entitled to all the treasure, he tries to go back to get it, but because he is stuck in the chest, he cannot climb the hill to get to it. He returns to shore to call his crew, but they never return.
Gaimon explains that over the years, several pirates have come to the island to find treasure, and Gaimon scared them off with his threats of curses. Nami and Luffy agree to retrieve the treasures for Gaimon as he is rightfully due for watching over them for so long. As they approach the hill, Gaimon is excited that the treasure he has longed for is finally within reach.
Luffy finds five chests at the top of the hill, but refuses to drop them. Nami is furious, but Gaimon has an inkling of what happened. After twenty years of guarding them, the treasure chest is revealed to be empty, looted before Gaimon ever set foot on the island.
Gaimon tearfully thanks Luffy and Nami for their kindness, despite learning the fate of the treasure. Although Gaimon is upset, Luffy calms him down by saying that in another twenty years, Gaimon could die without knowing the treasure is gone. He then offers him the chance to join his crew and find the One Piece, but Gaimon declines.
As Nami and Luffy leave, he explains that he already has another treasure to protect. Most of the people who come to the island are poachers who try to kill the strange animals on the island. After twenty years of guarding the treasure, he feels attached to them, and even though he doesn’t have the treasure, he can live happily and protect the island. Luffy promises that one day he will go and find One Piece.