Who are You?!

Summary
Kakashi checks Zabuza's pulse and, not being able to find one, concludes that the masked boy has killed him. Suspecting that the boy is a Kirigakure hunter-nin, Kakashi allows him to do as he wishes, telling Team 7 that it is the job of hunter-nin to track down and eliminate missing-nin like Zabuza. Naruto is angry that someone so young could kill someone as dangerous as Zabuza, but Kakashi informs him that it is something he will need to get used to. The boy leaves with Zabuza's body and Kakashi promptly collapses, having been left exhausted from overuse of his Sharingan. He is taken to Tazuna's home to rest. Kakashi later wakes up, and is surrounded by the genin, Tazuna and Tsunami (Tazuna's daughter). He states that he will recover from his use of the Sharingan in about a week. It is then Sakura questions him about the youth in the mask. Kakashi explains the hunter-nin, such as the youth, are part of the Anbu, the most elite and secretive shinobi within the Kirigakure. A shinobi's body, even in death, contains the secrets of their respective village, such as ninjutsu, chakra, as well as the ingredients of any drugs or special medicines used on them. Even dōjutsu, such as the Sharingan are valuable to an enemy. As such, in the case of a ninja betraying their village, the hunter-nin are dispatched, eliminate the missing-nin and dispose of their remains without any trace. Meanwhile, the boy revives Zabuza, having only pretended to kill him to save him from Kakashi.

Qui es-tu ? Siapa Kau?! pt-br:Capítulo 16: Quem é você?!