"The Secret Weapon is Called…" (隠し玉 名付けて…!, Kakushi Dama — Nazukete) is episode 15 of the Naruto: Shippūden anime.
Unable to escape from the visions that Itachi placed on him, Naruto mentally pleads with Sakura or Kakashi to free him from the genjutsu. He is then released by Sakura and Chiyo. Kakashi tells Naruto to stay alert, while he rushes towards Itachi. Itachi uses Fire Release: Phoenix Sage Fire Technique, which Kakashi is able to zip through and avoid. Itachi launches his Fire Release: Great Fireball Technique at Naruto, Sakura and Chiyo, and all three manage to avoid its path. Kakashi attempts to hit Itachi with his Lightning Cutter, but Itachi is able to jump into the air and evade the attack. However, Naruto attempts to hit Itachi in mid-air with his Rasengan. As Naruto makes contact, it turns out that that Itachi is a shadow clone. Kakashi uses the Hiding in Mist Technique that he copied from Zabuza years ago to shroud the environment. Itachi claims it useless as his Sharingan can still see through the mist, and attempts to hit Kakashi with his Fireball Technique. Kakashi muses that something is off about Itachi, and goes under the ground in an attempt to use Earth Release: Double Suicide Decapitation Technique, but Itachi manages to avoid Kakashi's attack. Holding Kakashi in place, Itachi attempts to cast a genjutsu on Kakashi. The Kakashi in his grip, however, is a shadow clone, that now has a hold on Itachi. Kakashi tells Naruto to hit both his shadow clone and Kakashi. Since Itachi was able to counter his Rasengan, Naruto recalls his training with Jiraiya, in which Jiraiya reminds him that Rasengan is a jutsu created by the Fourth Hokage, and that Naruto should use his unique chakra to improve and create his own unique Rasengan, which would be the most powerful technique in his arsenal. Naruto decides now is a good time to use it, and thus, using a shadow clone, rushes at Itachi and the Kakashi shadow clone with his Big Ball Rasengan. The attack hits Itachi, but Itachi smirks at Naruto right as he is hit. Sakura and Chiyo marvel at the destructive power of Naruto's technique.
After the technique subsides, the four are surprised to see that the dead body in front of them is not that of Itachi's, but of Yūra, an Anbu Commander and a Jōnin from Sunagakure. After Guy uses his Morning Peacock to destroy Kisame, Team Guy is surprised that the corpse lying in front of them is not that of Kisame's, but that of a stranger dressed in the Akatsuki cloak. Guy reaffirms his original feeling that he has never met the man lying in front of them before.