Shinnō

was the main villain in Naruto Shippūden 2: Bonds. He was a sensei of Amaru.

Background
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. He also accepted Amaru's request to take her as an apprentice in the medical arts.

Abilities
Despite having little care for human life, Shinnō demonstrated remarkable medical knowledge and prowess without the aid of chakra. With only basic medical tools, he performed flawless surgeries to save people from near death. In addition to the human body, Shinnō also demonstrated great knowledge of the human mind. He had repeatedly shown himself able to understand how a person thinks and exploit it to suit his needs. He used this ability against Amaru, saying that you never suspect the one that saves your life.

In terms of ninjutsu prowess, Shinnō's skills focused more on his knowledge of chakra and human physiology. He could easily injure a person to the point of appearing dead, using a jutsu to resurrect the person, even if it was himself. He had also shown high sealing jutsu prowess as he was the one who sealed the Zero-Tailed Beast within Amaru.

With his knowledge of Dark Chakra, Shinnō was shown as able to unleash a powerful transformation to take a human being well beyond the normal limitations. By combining his special jutsu with the dark chakra, Shinnō was able to transform into a superhuman body that can freely access his chakra without hand seals or any apparent effort of chakra build-up. He was even able to unleash powerful shock waves of dark chakra and freely access all Eight Gates without any drawbacks as long as he still had access to enough dark chakra.

Plot overview
When first introduced he and Amaru came to Konohagakure to get help for their village when Soragakure appeared. During which, he demonstrated tremendous medical prowess by saving the lives of several near-death victims from the Soragakure's attack. He and Amaru were 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 off a trap, Shinnō quickly jumped in to save her seemingly at the cost of his own life.

Later, he reappeared perfectly fine and revealed he used a special jutsu to create the illusion of death. He also revealed his affiliation with the Sky Ninja and that the kind doctor he portrayed for years was nothing but a lie to gain Amaru's trust. He also revealed to have been the one who sealed the Zero-Tailed Beast within her to gather as much Dark Chakra from the villagers as possible. He then used the dark chakra to transform into what he called the "Ultimate Body", gaining tremendous physical prowess and the ability to freely manipulate his chakra.

Initially, Shinnō repeatedly and effortlessly demolished Naruto despite all his attempts, but after Naruto realized Shinnō's power came from Amaru's negative emotions from feeling betrayed, Naruto helped her to let go of those feelings, stripping Shinnō of his power source and enabling Naruto to defeat him. Before the final blow could be made, Sasuke appeared and intervened as he was ordered by Orochimaru to retrieve the man.

Already seeing through Shinnō's power, Sasuke used his Chidori Senbon to disrupt Shinnō's chakra flow, tricking Shinnō to strip himself of all his power and reducing him to a withered old man. Growing desperate, Shinnō retreated to a chamber with the main source of dark chakra. There, he merged with the Zero-Tailed Beast's seedling and attempted to finish off Naruto and Sasuke once and for all. But once the two unleashed the Nine-Tail's and the Cursed Seal's chakra, they were able to overfeed the cocoon, which caused it to release them. Naruto released demon fox chakra then began to get absorbed back into the Rasengan he created, creating the Tornado Rasengan. Shinnou puts up a barrier to defend himself from the attack and Naruto Tornado Rasengan hits the shield and the two reach a stalemate. Sasuke uses his Sharingan to see Shinnō's weakness which is the large tower that he is connected to. Sasuke activates his second Cursed Seal form and cuts the tower deactivating Shinnō's shield and allowing him to be hit by Naruto's Tornado Rasengan, killing him.