Yashamaru (夜叉丸) was an Anbu from Sunagakure. He was also the right-hand-man of the Fourth Kazekage.[3] Yashamaru's elder sister, Karura, died shortly after giving birth to her youngest son Gaara, within whom the One-Tailed Shukaku had been sealed. After her death, Yashamaru was appointed as Gaara's caretaker by the Fourth Kazekage. Unlike his fellow villagers, he attempted to understand his nephew's plight as a jinchūriki, and believed that the sand that flew to Gaara's aid in moments of danger was actually the will of Karura protecting her child.[4][5][6] However, when Gaara's inability to control Shukaku proved a problem, the Fourth Kazekage tasked Yashamaru with the duty of attacking the boy both physically and psychologically to test his actual mastery over the beast's power. Yashamaru reluctantly accepted his role in order to teach Gaara about physical pain, emotional pain and love.[7] The test became a suicide mission after Yashamaru was gravely injured by Gaara's Sand Binding Coffin. He lied to Gaara, telling him that he hated him and that his sister gave him his name from the phrase "a self-loving carnage" (我を愛する修羅, Ware o aisuru shura) to reflect the undying hatred she felt towards the village, rather than out of love for her son. Yashamaru then told Gaara that nobody would ever love him, and then detonated a series of explosive tags hidden within his flack jacket in an attempt to take Gaara with him. Yashamaru's cruel words and his suicide caused Gaara to become a sociopath and even more of an emotional wreck than he already was.[8][9]

It would only be years later during the Fourth Shinobi World War that Gaara learned the truth of the mission he was given and that he had in fact lied to him about his mother under direct orders from the Fourth Kazekage.[3]