The Great Treasure of Tongari Island

The Great Tongari Island Treasure Hunting Adventure is a short animated film that exclusively plays in Tokyo One Piece Tower's "Luffy's Endless Adventure" exhibit. It debuted on April 21, 2018.

The Straw Hat Pirates reach Tongari Island and seek to find a secret treasure Trafalgar Law told them about. However, things are not as they seem, and they soon get into conflict with Law and the Marines.

Summary
The movie begins with the Straw Hat Pirates sailing on the Thousand Sunny, and they look on with excitement as they approach Tongari Island. After making landfall, the Straw Hats feast on the island's food, explore the island's shops and play roulette in a casino.

Walking around the island, the crew (minus Franky and Brook) find a cave Trafalgar Law told them about and walk inside. At the entrance, they almost immediately find a treasure chest, and Robin becomes suspicious. Luffy opens the chest with excitement only to find Tongari Den Den Mushi asleep inside. He wakes up, commenting on his nice nap, and a frustrated Nami picks him up and shakes him, angry that he is not treasure. While Luffy laughs at Nami, Law walks in. Nami holds up Tongari and accuses Law of lying to them about the island having a secret treasure. Law reaffirms that the legend of the island's treasure is true, but he explains that he did not call them to the island. A large Seastone cage falls on top of the crew, trapping them inside. Luffy tries to confront Law, but he becomes weak immediately after touching the cage's bars. Kizaru appears behind Law, commenting on how easy it was to capture the Straw Hat Pirates. The crew is shocked, and Kizaru reveals that Law helped him to catch them. They are surprised at Law's betrayal, and Franky calls through their Den Den Mushi to provide assistance.

Manning the Thousand Sunny, Franky shoots the Gaon Cannon into the cave, causing Tongari Den Den Mushi to bounce around in the rubble and free his crewmates. Kizaru tries to attack the crew, but Law stops him. Luffy tells his crew to continue running as he settles unfinished business with Law. Running through the island's forest, the rest of the crew questions why Law betrayed them. They come up to the coast to see a fleet of Marine battleships, and Issho charges toward them, clashing with Zoro. Sentomaru jumps from the ships as well, attempting to strike Sanji. Nami calls Luffy through Tongari Den Den Mushi and warns him to run away, but Luffy is adamant about confronting Law. Law creates a Room and Luffy activates Gear Second. As Law slashes at him, Luffy blocks with his forearms embedded in Busoshoku Haki, begging Law to stop. Zoro and Issho continue to exchange blows, clashing with Zoro's Kokujo: O Tatsumaki and Issho's Gravito Moko. Sanji and Sentomaru also clash, with Sanji using Poêle à Frire: Spectre and Sentomaru using Ashigara Dokkoi. Law uses Tact to launch a large boulder at Luffy, which he destroys with Elephant Gun. However, this proves to put Luffy at a disadvantage, as Law now has many smaller rocks to bombard the captain with at once.

Kizaru and Tongari Den Den Mushi watch as the two were about to clash again when Bepo speaks through Tongari to inform Law that their crew has been saved by Nami, Robin, Usopp, and Chopper. Law apologizes to Luffy, but before they can leave, Kizaru attacks them with Yasakani no Magatama. Law and Luffy are knocked to the ground, and Nami and Bepo plead for them to escape through Tongari. The two stand up and prepare to fight. Kizaru uses Ama no Murakuma, and Luffy activates Gear Fourth: Boundman. Luffy and Law clash with Kizaru using Gomu Gomu no Kong Gun and Injection Shot, respectively. As they struggle to overcome the admiral, their friends call out to them to win. Suddenly, Tongari Den Den Mushi begins to glow, along with the rest of the island’s Den Den Mushi. Their energy is channeled through the island into the central tower, which begins to radiate light. The light from the tower concentrates into a beam that gives Luffy and Law enough power to overwhelm Kizaru. Sanji, Zoro, Issho and Sentomaru stop fighting as they watched in awe at Kizaru's defeat.

Kizuru, Issho, and Sentomaru return to their ship, and Kizaru comments on Tongari Island’s troublesome power. Luffy and Law lay on the ground, exhausted. A narrator explains that this power was handed down for generations on Tongari Island since ancient times and was hiding with Tongari Den Den Mushi, who only lived on the island. This power is a special psychic wave that has the power to amplify Haki, and it is activated by strong bonds of friendship, like the ones held by the Straw Hat and Heart Pirates. The animation ends as the two crews reunite and throw a party to celebrate.