Naozumi Saitō (斎藤 直純 , Saitō Naozumi) is a character found only in the Gantz anime.
He was a troubled business man, who owed a lot of money.
In the beginning we see him at the station as Masaru Kato and Kei Kurono are running away from the train. Before getting to the Gantz room, he was chased by a couple of loan sharks. Cornered and afraid, he decided that death was better for him and he threw himself into the path of a speeding train. Because he suicided himself, Kurono assaulted him, telling him that others that suicide had changed after they came here. Despite that he remains jumpy and has difficulty trusting anyone during the mission and he even threatened to kill several people. After the group splits up he gets killed by a shot from Hajime Muroto.