Episode 820 - Luffy's Ultimate Oath! The War to Protect the Pirate King's Lineage

Episode 820
Luffy’s Ultimate Promise! The Battle to Protect Pirate King’s Legacy
Japanese: ルフィの究極の約束！海賊王の遺産を守るための戦い
Rufi no Kyūkyoku no Yakusoku! Kaizoku-Ō no Isan o Mamoru Tame no Tatakai

The Straw Hats face off against the ancient warriors, each battling their way through the island’s most dangerous challenges. As they uncover the island’s secrets, the crew learns about the history of the Pirate King and the true nature of the One Piece. With the final pieces of the puzzle in place, the Straw Hats prepare for the ultimate confrontation.