Shinnou was the sensei of Amaru. He came to Amaru's village 15 years ago and after saving her life from a terrible illness, he was welcomed as a member of the village. During which, he revealed to be a former ninja who turned away from the path of battle to help save lives instead. When first introduced he and Amaru came to Konoha to get help for there village when the Sky Ninja appeared. During which, he demonstrated tremendous medical prowess be saving the lives several near-death victims from the Sky Ninja's attack. He and Amaru where then escorted back to their village by Naruto, Sakura, and Hinata. To their horror, when they arrived they found the village in ruins. When Amaru accidentally set of a trap, Shinnou quickly jumped in to save her seemingly at the cost of his own life.