Not long ago,they was a war between the Shinobi nations during that war,they were two Shinobis in a hidden place far from their home town which is the hidden leaf village during that war,the two Shinobis were married and they were about to give birth to a child.when they gave birth to shadow,an unknown Shinobi from the hidden cloud village tried to kill the baby but the father shadow stopped him but could stop him before the hidden cloud shinobi killed the mother of shadow.shadow's mother died when his father was trying to save shadow,the father of shadow was a strong and fast Shinobi so he kept shadow in an apartment in the leaf village and went to the battlefield to join the other but none of the Shinobi that went to the war survived including shadow father but the 3 third hokage survived and the 3 legendary Sannin survived and one of the legendary Sannin was shadow's father sensei.