Chibi

was an abandoned dog that Nagato found while wandering around the streets after his parents were killed.

Background
While wandering around the war-torn Amegakure, Nagato collapsed due to hunger. On the verge of death, he was approached by Chibi, who gave him the will to go on. They were later found by Konan, who shared her food with them. Chibi and Nagato joined up with Yahiko and Konan, stealing food from local vendors. The Ame Orphans later wandered too close to the battle between Hanzō and the Sannin, and Chibi was killed in the crossfire. The orphans later buried him and mourned for his loss.

Trivia

 * Chibi means "tiny".