Nami skillfully repairs the straw hat damaged by Buggy, much to Luffy’s delight. He expresses his gratitude to Nami for her kind deed. Soon, they come across an intriguing island, and despite Nami’s initial reluctance, Luffy decides to explore it in search of another crew member. Meanwhile, Zoro takes a much-needed nap to recover from his injuries.
As Luffy and Nami venture into the isolated island, they encounter peculiar and bizarre animals, like a mix of hen and fox, lion and pig, making the place seem even more unusual and extraordinary. Suddenly, they hear a voice from above, the forest guardian’s warning, urging them to leave to avoid facing dire consequences. However, undeterred by the caution, Luffy pays no heed to the warning and continues his exploration.
Unexpectedly, Luffy finds himself being targeted by a bullet shot, but being a rubber man, he effortlessly deflects it. To their surprise, the forest guardian is none other than Luffy himself, and they soon discover the man trapped in a box named Gaimon. Luffy showcases his powers to Gaimon, who recounts his unfortunate fate of getting stuck in the treasure box two decades ago and has since been living alone on the island. Luffy tries to help him but realizes that Gaimon’s body has merged with the box, making it impossible to free him without causing harm.
Luffy shares his dream of finding the legendary One Piece and exploring the treacherous Grand Line. Despite possessing a map, neither Gaimon nor Luffy knows how to read it. Nami comes to their aid, explaining the concept of two oceans separated by the Red Line, and the Grand Line, a perilous and dangerous sea often referred to as the pirates’ graveyard. Only the legendary pirate Gol D. Roger successfully navigated this route to find the hidden treasure, the One Piece.
Listening to the tales of the Grand Line, Gaimon’s memory is refreshed, and he recounts how he ended up trapped in the chest box. Two decades ago, Gaimon was part of a pirate crew searching for hidden treasure on the island. They found nothing but an empty chest, and while his crew decided to move on, Gaimon felt compelled to search further. Climbing a large rock hill, he discovered the treasure, but in an unfortunate twist of fate, he got stuck in the chest and was abandoned by his crew.
With Gaimon revealing the location of the large empty hill where treasure chests are kept, he warns them that the treasure is his alone. As they reach the location, Luffy climbs up the hill and retrieves one chest, but he hesitates to hand it over to Gaimon. Nami is irritated by this, but Gaimon appreciates Luffy’s concern. To their surprise, all the treasure chests are empty. Luffy decides not to break Gaimon’s belief and make him feel bad for protecting empty chests for two decades.
Luffy extends an invitation to Gaimon to join his crew, but the forest guardian declines, as he has a duty to protect the forest and its rare animals. Grateful for their help, Gaimon bids farewell to Luffy and his crew, wishing them luck in their quest to find the One Piece.