Shinnō

was the main antagonist 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 accepted Amaru's request to take her as an apprentice in the medical arts, but secretly implanted the Zero-Tailed Masked Leech into her in order to gather a large amount Dark Chakra from the villagers for the years to come. He also once taught Orochimaru several forbidden Reincarnation Ninjutsu.

Appearance
Shinnō is an elderly man with long grey hair that flows out at the back, and a beard that extends from the sides of his face of the same colour. His eyebrows are thick and of a darker grey, but neatly trimmed. He also has yellow eyes with dark bags around them, and tear troughs under them, giving a somewhat stern look, similar to Itachi and Fugaku Uchiha.

He wears a black shirt with a white gi with brown and blue edges over it, and further a sleeveless red jacket with gold sidings over that, and simple blue pants. He also originally wore a dark red bandanna, which he gave to Amaru before his presumed death.

After using the Body Revival Technique in combination with Dark Chakra to increase his strength, Shinnō underwent a great physical change in his body: his hair and beard grew wild and much longer, as well as blackening in colour. His eyebrows became black and wildly thicker. His muscles greatly expanded, which caused his clothes on his upper body to burst, leaving him bare-chested, with only shreds of the sleeve around his wrists. All this made him look younger and much more physically fit. The creases under his eyes and the dark bags around them also seem to have disappeared.

However, after being struck by Sasuke in his tenketsu and causing a backlash in his attempt to use Dark Chakra, Shinnō became a heavily emaciated old man, with his hair turning grey again and falling out, leaving him beardless, no eyebrows, and bald on top, with only wisps of hair at his side, and stubble in where his eyebrows and beard used to be. The creases under his eyes also return.

Personality
At first, Shinnō appeared to be a very kind-hearted doctor whose purpose in life was to save lives of others. He would turn away from battle in order to prioritize his motives of saving as many people as possible, and not be prejudiced with who the patient is: he saved Amaru from a terrible illness despite her having a monster inside her, and then accepted her as a disciple in the medical arts. He was also encouraging, as when Amaru emulated to look like him, which led to the other villagers to laugh, Shinnō instead complimented her, and encouraged her to work hard to achieve her dreams. Shinnō's desire to save lives led him to be fully willing to sacrifice his life to save Amaru from a trap, and giving her his bandanna as a way of entrusting everything to her.

However, this was all later proven to be a façade; Shinnō's true character is manipulative, cruel and arrogant. He worked for fifteen years undercover as the kind doctor, earning the trust of the people, in order to harvest a large amount of Dark Chakra from them, going as far as to plant the Zero-Tailed Masked Leech into an innocent child, Amaru, as the seed, and then acted kind to her for all the time to discreetly accomplish his true goal. He had no care for other people's lives, despite his incredible medical skills, and uses his knowledge of the human psychology to manipulate their emotions and actions. When the truth came out, he ruthlessly sneered at Amaru's despair, claiming that if anything is weird, is how he acted for the last fifteen years, that he never once considered their master-student relationship to be anything more than nonsense, snatching back the bandanna he gave her and ripped it to pieces, and mockingly laughed at her confession of her love for him. He is also very arrogant, as he claimed that the throne inside the Ancor Vantian worthy of a king, which he thought to be himself, and brutally assaulted Naruto for damaging it, even when he was the one who threw him against the throne, and giving himself the title. After being stripped of his powers by Sasuke's attack, Shinnō lost his composure, and tends to shout out loud of the capabilities he has when merged with the Zero-Tailed Masked Leech, and the consequences of its release.

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 people think and exploit it to suit his needs. He used this ability against Amaru, saying that people never suspect the one that saves their life. With this advantage, he is a very skilled manipulator, acting as a kind-hearted doctor for 15 years, while discreetly implanting the Zero-Tailed Masked Leech into Amaru and having it to collect the hatred within the village. He pretended to sacrifice himself for Amaru in order for her to release the tailed beast's full powers.

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. He also knew many Reincarnation Ninjutsu, which he taught to Orochimaru, and a reason why Orochimaru wanted Sasuke to bring Shinnō back to Otogakure, believing that the doctor may help extend Orochimaru's host's vitality.

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 signature Body Revival Technique 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. This form manipulates the understandings of "Destruction and Rebirth" of muscles that makes it stronger to increase the body's strength. He was even able to unleash Dark Chakra in forms of powerful widespread or condensed shock waves or bolts for tremendous internal damage and claimed to be able to freely access all Eight Gates without any drawbacks as long as he still had access to enough Dark Chakra. Upon being injured by Sasuke, Shinnō merged with the Zero-Tailed beast to gain its powers and Dark Chakra, as well as manipulating the flying fortress Ancor Vantian. While powerful, the Dark Chakra eventually destroys the user's mind and rots the soul, which may explain Shinnō's increasing instability as he nears his end.

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 surrendered to Sasuke the scroll bearing the secrets behind his Body Revival Technique (he reasons that Orochimaru was purely interested in the contents of the scroll itself, not him), buying enough time for him to retreat to a chamber housing both the main source of dark chakra as well as the Zero-Tails. 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. Shinnō 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, ripping him and the Zero-Tailed Masked Leech from the stone wall that the cocoon was bound to. With the beast freed from its rein, Shinnō creepily emerged in a snake-like fashion, taunting the two for releasing the demon from its shackles, before it burst out of his emaciated body in a berserk mode, killing him once and for all.