Shinno was a person who taught Orochimaru some forbidden techniques related to regeneration. Around thirteen years before the series started, Shinno came to a village in the Land of Fire. He pretended to be a former ninja who had turned away from fighting to save lives.

But the truth was different as he was actually a spy from the Land of the Sky, sent to find a special scroll that could unlock the powers of the Zero-Tails. His goal was to use this power for his own country to try to take over the world.

After a few years in the village, Amaru, who had lost her parents, got very sick. The villagers were afraid of getting sick, too, so they kept away from her. But Shinno went to her home and performed a long and challenging surgery to save her life. His actions made him a hero in the village, and he agreed to be Amaru's mentor in medical skills. However, secretly, he had a hidden plan. His real goal was that he wanted the Zero-Tails to absorb the negative emotions of the villagers over many years to gather a lot of Dark Chakra. When the Land of the Sky appears, Shinno and Amaru first appear when he comes to Konohagakure for help.

He shows remarkable medical skills by saving people from the Land of the Sky's attack. Naruto, Sakura, and Hinata help them return to their village. But when they get there, they find the village destroyed. When Amaru sets off a trap accidentally, Shinno seems to sacrifice himself to save her.

However, he reappears unharmed and reveals he used a special technique to make it look like he died. He also tells Amaru that he was never the kind doctor he appeared to be; it was all a lie to gain her trust. He confesses to harvesting the Dark Chakra of the Zero-Tails from the villagers and uses it to transform into what he calls the "Ultimate Body," giving him great strength and chakra control.

In their first fight, Shinno easily defeats Naruto, but they realize his power comes from Amaru's negative emotions because she feels betrayed by him. Naruto helps her let go of those feelings, weakening Shinnō. Before they finish him, Sasuke arrives on Orochimaru's orders to retrieve Shinno. Seeing through Shinno's power, Sasuke disrupts his chakra flow, taking away his power and making him weak.

Desperate, Shinno gives Sasuke the scroll with the secrets of his Body Revival Technique. He then retreats to a chamber where the main source of dark chakra and the Zero-Tails are located. There, he merges with the Zero-Tails' seedling and tries to defeat Naruto and Sasuke. But with the power of the Nine-Tails and Sasuke's Cursed Seal, they overfeed the cocoon, which causes it to release them.

Naruto releases his demon fox chakra and creates the Tornado Rasengan. Shinnō puts up a barrier to defend himself, and a stalemate ensues. Sasuke uses his Sharingan to find Shinno's weakness, a tower he's connected to. Sasuke cuts the tower with his second Cursed Seal form, deactivating Shinno's shield. Naruto's Tornado Rasengan hits Shinno, ripping him and the Zero-Tails from the wall where the cocoon is bound. When the Zero-Tails is released, it berserk, killing Shinno for good.

At first, Shinno seemed like a really kind doctor who cared about saving lives. He put others before himself and even helped a girl named Amaru when she was very sick. He encouraged her to follow her dreams and was willing to risk his life to save her from a trap. He gave her his bandanna as a sign of trust.

But later, it turned out that this was all an act as Shinno was actually a manipulative, cruel, and arrogant person. He spent fifteen years pretending to be a good doctor, gaining the villagers' trust. His real goal was to collect a special kind of dark energy called Dark Chakra from the villagers using the Zero-Tails. Despite his amazing medical skills, he didn't care about the lives of the people he helped. He used his knowledge of psychology to control their emotions and actions.

Shinno was heartless when the truth came out and made fun of Amaru's despair. He said their master-student relationship was meaningless, tore the bandanna he gave her, and even laughed at her when she confessed her love for him. He was also very full of himself, thinking he deserved to be a king and calling himself the "Sky Emperor."

After losing his powers due to Sasuke's attack, he became frantic and loudly talked about what he could do when merged with the Zero-Tails and the consequences of its release.

Shinno was an elderly man with long, flowing gray hair that extended down his back. He had muttonchops connected to a beard of the same gray color. His eyebrows were thick, darker gray, and neatly trimmed. He had yellow eyes with dark bags underneath, which gave him a somewhat stern look. His eyes appeared kind and generous in his false persona, but they changed to an arrogant and sadistic look when his true colors were revealed.

He wore a black shirt with a white gi that had brown and blue edges over it. On top of this, he had a sleeveless red jacket with gold sidings. He completed his outfit with simple blue pants. Additionally, he initially wore a dark red bandanna, which he later gave to Amaru.

Shinno used the Body Revival Technique combined with Dark Chakra to enhance his physical abilities. As a result, his appearance changed significantly. His hair and beard grew much longer and turned black. His eyebrows became thicker and black.

He grew taller, and his muscles expanded, causing his upper body clothing to burst, leaving him bare-chested with shreds of sleeves around his wrists. These changes made him look younger and more physically fit. The dark bags and creases under his eyes seemed to have disappeared.

Following a confrontation with Sasuke, where he was struck in his tenketsu and experienced a backlash from using Dark Chakra, Shinno's appearance deteriorated drastically. He became heavily emaciated, his hair turned gray again, and most of it fell out. He lost his beard and eyebrows, becoming bald on top with only small wisps of hair at the sides and stubble where his eyebrows and beard used to be. The creases under his eyes returned, giving him a feeble and aged look.

Shinno's Medical Expertise

One of Shinno's remarkable traits was his exceptional medical knowledge and prowess. He possessed the ability to perform complex surgeries using basic tools, even without the use of chakra. This expertise allowed him to save people from the brink of death.

It's important to note that Shinno had little regard for human life, which made his proficiency in medical techniques all the more unsettling.

Understanding of Human Psychology

Shinno also demonstrated a deep understanding of human psychology. He could grasp how people think and exploit their vulnerabilities to suit his needs. This skill made him a master manipulator. He once told Amaru, a character in the story, that people often do not suspect the one who saves their life.

Shinno used this advantage to his benefit, as he posed as a kind-hearted doctor for 15 years, all the while secretly gathering Dark Chakra from the villagers' hatred of the Zero-Tails.

Ninjutsu Prowess

In the realm of ninjutsu, Shinno's abilities primarily focused on his extensive knowledge of chakra and human physiology. He excelled in the art of Regeneration Techniques, having mastered many of them.

He was even skilled enough to teach these techniques to the notorious ninja Orochimaru, who held Shinno's abilities in high regard. Orochimaru expected that Shinno had invented more regeneration techniques and was confident that Shinno could extend the vitality of his hosts.

Body Revival Technique

One of Shinno's signature techniques was the Body Revival Technique, which he combined with Dark Chakra to achieve a powerful transformation. In this form, he underwent a significant physical change, surpassing normal human limitations. He claimed that this transformation represented the ultimate body.

Shinnō gained the ability to access his chakra freely, without the need for hand seals or any visible effort of chakra buildup. This level of control was so advanced that he believed he could withstand the release of all Eight Gates, a technique that would prove fatal for most other individuals.

Enhanced Physical Abilities

Shinno exhibited great physical strength in his transformed state. He used this strength to brutalize his opponents, such as Naruto, with powerful punches that sent them flying and shattered structures upon impact. Shinnō's speed was so remarkable that it appeared he could teleport behind his opponents, making him a formidable force in combat. This transformation manipulated the concept of "Destruction and Rebirth" of muscles, making them stronger and enhancing his physical prowess.

Dark Chakra Manipulation

Shinnō's knowledge of Dark Chakra was another key aspect of his abilities. He could unleash Dark Chakra in various forms, such as powerful shockwaves and bolts.

These attacks caused significant internal damage to his adversaries. This dark and malevolent energy was a source of great power for Shinnō and played a crucial role in his confrontations.

Merge with the Zero-Tails

Shinno's powers extended further as the story progressed. He merged with the Zero-Tails, gaining its powers and control over the flying fortress Ancor Vantian. This fortress was activated and controlled through a seal, showcasing Shinno's mastery of Fuinjutsu.

However, it's important to note that, despite his formidable abilities, Shinnō's association with Dark Chakra eventually took its toll. The Dark Chakra began to cause him to deteriorate mentally and physically, leading to his increasing instability as he neared the end of his role in the story.