The Demon in the Snow

is episode 19 of the original Naruto anime.

Synopsis
Gatō tells Zabuza that he planned to betray him from the beginning and orders his men to kill the Missing-nin. Zabuza tells Kakashi that their fight is over, and Kakashi agrees. Gatō kicks Haku's dead body, which infuriates Naruto, but Zabuza is unfazed, saying he only used Haku as Gatō used him. Naruto cannot accept this and begins to cry, saying that Haku loved Zabuza and gave everything so that Zabuza could accomplish his goals. Moved by Naruto's tears and words, Zabuza reveals that he is crying as well and acknowledges Haku's sacrifice. Without the use of his arms that have been immobilized by Kakashi, Zabuza borrows Naruto's kunai, taking it in his teeth, and he charges at Gatō. Zabuza is stabbed multiple times by Gatō's thugs but still manages to kill the mob boss despite severe injuries. Meanwhile, the rest of Team 7 are relieved to discover that Sasuke is still alive, having been purposely spared any lethal injuries by Haku. Gatō's men are scared away by the villagers of the Land of Waves who arrive to defend Tazuna and their village. Afterwards, Zabuza requests that Kakashi place him beside Haku. Before dying, Zabuza says that he wants to go to the same place as Haku, and Kakashi says that he believes they'll go to the same place together. Team 7 bury the two ninja, leaving Zabuza's sword, Kubikiribōchō, as a marker for his grave. Naruto is unsatisfied with the prevailing notion that ninjas should strive to become merely tools, and he declares that he will find his own ninja way. He says goodbye to Inari, and the team returns to Konohagakure. Tazuna decides to name the finished bridge the Great Naruto Bridge.

Trivia

 * In the manga, when attacking Gatō, Zabuza cuts his head off, rather than slashing him up and pushing him into the sea.