Episode 407 - The Last Treasure! Luffy and His Crew Face Their Greatest Challenge

Episode 407
The Last Treasure! Luffy and His Crew Face Their Greatest Challenge
Japanese: 最後の財宝！ルフィと仲間たち、最大の試練
Saigo no Zaihō! Rufi to Nakama-tachi, Saidai no Shiren

The Straw Hat Pirates finally defeat the mercenaries and discover the true nature of the weapon. However, they also uncover disturbing information about a new threat rising in the Grand Line. With their mission to protect the island complete, the crew sets sail once again, determined to continue their journey.