Osoi (オソイ, Osoi) was a genin-level shinobi from Kumogakure who once fought alongside Toroi. He was also the father of Musai.

Osoi fought alongside Toroi in his last battle, which lead to his own death. He was later mistakenly reincarnated by Orochimaru in an attempt to reincarnate Toroi. After explaining the mix-up to Orochimaru and Kabuto, they decided to keep him around for future use.

During the Fourth Shinobi World War, Kabuto deployed Osoi, who he saw as one of his weaker assets, in an attempt to unseal his other, stronger pawns. During a scuffle between Kabuto's weaker pawns and the Allied Shinobi Forces, Osoi spotted his son Musai. After they talked for a while, Osoi was sealed. Later, when the Impure World Reincarnation Technique was canceled, his soul was returned to the afterlife.

Anime Debut: Naruto Shippuuden Episode #316

(Source: Narutopedia)