Assassin of the Moonlit Night (月夜の暗殺者, Tsukiyo no Ansatsusha) is episode 76 of the original Naruto anime.
Seeing Naruto and Sakura's determination to protect Sasuke, Gaara remembers his childhood with his uncle Yashamaru. While Yashamaru had for many years been the only person who seemed to care for Gaara, Yashamaru in reality hated him. Yashamaru attacked him as such, forcing Gaara to fight the only person who ever loved him.
Yashamaru betrayed Gaara by trying to kill him after that day Gaara has never been the same Yashamaru told Gaara about love so when Gaara is defeated by naruto Gaara remembers Yashamaru.