The Four Emperors Saga (四皇編 Yonkō Hen?) is the third saga of the second half of the anime and the manga series, One Piece, and is the ninth saga overall.
The Ninja-Pirate-Mink-Samurai Alliance is formed to take down Kaido of the Four Emperors and the shogun of Wano Country, and Luffy becomes entangled with another Emperor, Big Mom, as he seeks to retrieve his crewmate Sanji from her plans. Meanwhile, the royalty of the World Government gathers for the Levely, and the Revolutionary Army makes their move, leading to a huge change in the world's powers.
- This is currently the longest saga in both the manga and anime.