The Fourth Shinobi World War: Countdown arc is the prelude to the main war. Tobi (masquerading as Madara) and Kabuto form an alliance, declaring war on the Five Great Shinobi Nations. The allied villages prepare for battle, while Naruto and Killer Bee are sent to a hidden island to train and secure the Tailed Beasts
On the Turtle Island, Naruto trains with Bee to master the Nine-Tails' chakra. He confronts the dark side of his own heart and even meets the chakra manifestation of his mother, Kushina Uzumaki, who helps him seal Kurama.
Sasuke receives his deceased brother Itachi's eyes, successfully acquiring the Eternal Mangekyō Sharingan to avoid losing his sight.
Kabuto Yakushi aligns with Tobi but secretly pursues his own goals. He uses the Edo Tensei (Impure World Reincarnation) to resurrect deceased, legendary ninja to bolster the Akatsuki army
Both sides engage in a race for intel. Kisame infiltrates the Turtle Island to track Killer Bee, but is eventually defeated and captured by Might Guy.