The First and Last Opponent

is episode 266 of the Naruto: Shippuden anime.

Summary
Suigetsu and Jūgo escape from their imprisonment within the Land of Iron, due to weakened security caused by the mobilisation of forces for the war. Suigetsu ask Jūgo whether he would like to help him find his sword. While searching for his sword, Suigetsu explains why he wants to obtain the seven swordsmen's weapons, and explains their abilities. Meanwhile, the Third Division battles the revived Seven Ninja Swordsmen of the Mist and Kakashi comes up with a plan. Kakashi nearly hits Zabuza, but is stopped, and held by Haku who protects Zabuza. Zabuza cuts through both Haku and Kakashi but he narrowly manages to avoid Zabuza's attack. Kakashi and Zabuza strike simultaneously and Kakashi manages to pierce Zabuza. Zabuza and Haku are then captured and restrained. Here, the Second Division fights the White Zetsu Army who erupt from underground. Kitsuchi is informed that thousands of more Zetsu, travelling underneath, have already gone past them. Gaara discovers Mū, the Second Tsuchikage with his sand.