S1, E16: Their vanquished foes, Kisame and Itachi, turn out to be doppelgangers whose appearance and powers were copied with the Impersonation Jutsu. Chiyo and Kakashi realise that the attack was just a diversion, and that the Akatsuki have already begun the process of extracting the Tailed Beast from Gaara. Granny Chiyo explains to Naruto and Sakura the connection between the Tailed Beast and the Jinchuriki, the host body. The shocking disclosure hits home, and Sakura realises that Naruto faces the same fate and sheds silent tears.