Shin Uchiha

was a former test subject of Orochimaru. After developing a fixation on the Uchiha clan, and more specifically Itachi Uchiha, he took the Uchiha name for himself and left Orochimaru, taking his "sons" with him. Believing that peace was detrimental to human evolution, Shin began a plot to revive the Akatsuki so that the ensuing conflict would be a catalyst to further human evolution.

Background
Shin was one of Orochimaru's experimental test subjects and followers, and possessed a unique genetic make-up that allowed for tissue and organ transplantation with absolutely no chance of rejection. Together they performed various experiments, cultivating clones from Shin's teeth and nerves in order to uncover many secrets of genetics.

At some point Shin became intrigued by the Uchiha clan, especially Itachi Uchiha. As such, he began to imitate the Uchiha: adopting their surname and customary clothing, as well as numerous Sharingan which have been implanted all over his body. His Sharingan-embedded right arm was harvested by Orochimaru and transplanted to Danzō Shimura along with some of Hashirama Senju's cells. Some time after this, Shin left Orochimaru's side and took most of his clones with him.

Personality
Shin is a pragmatic, scientific individual who adheres strongly to the evolutionary principles of survival of the fittest and natural selection, believing that living organisms are slaves to their genes and exist only to survive by passing on their strongest traits to the next generation. As such, he sees conflict as a necessary component of mankind's evolution and seeks to revive Akatsuki and bring an end to the peace of the world, which he believes will cause the human species to stagnate and ultimately become extinct.

Though he refers to his clones as sons, he appears to have no fatherly affection for them, instead viewing them as extensions of his own life who should be sacrificed for the sake of his continued survival. He demonstrates this lack of emotion by using one of his clones as a human shield, then harvesting the clone's vital organs to surgically replace his own, killing the clone in the process.

Though typically logical, Shin has a peculiar fascination with Itachi Uchiha and has adopted the Uchiha surname as his own, going so far as to outfit his clones in the clan's customary attire. He has come to loathe Sasuke Uchiha, blaming him for the death of Itachi and bringing shame to the Uchiha clan. He wishes to "avenge" Itachi by killing Sasuke, even going as far as to capture Sasuke's daughter, Sarada Uchiha, to use her in pursuit of his goals.

In battle, Shin has no sense of honour and will resort to any dirty tactics to win. One example being he took advantage of Sasuke's fatherly instincts and attacked Sarada, forcing Sasuke to shield her with his body.

Appearance
Shin is a tall, pale, and bald man. He also has no teeth, having used them all for his genetic experimentation. He also had his right arm amputated up to the bicep. He has a horizontal scar that runs from his right temple to the bridge of his nose, over his right eye, which is held open by eight stitches and houses a bloodshot, implanted Sharingan with slightly red sclera. He has numerous additional Sharingan implanted all over his body: one in his left eye socket, six visible on his left arm, one on his right shoulder and one on the left side of his chest, and at least three on his head.

He first appears garbed in a dark, hooded cloak, later discarding it to reveal a dark, long-sleeved, high-collared cloak bearing an Akatsuki cloud emblem on both its front and back, as well as dark pants and boots. His right arm, typically hidden by his long sleeves, has been severed above the elbow.

Abilities
Shin was a highly capable combatant and strategist, such that he could nearly defeat Sasuke Uchiha through misdirection before Sakura's intervention. During his battle with Sakura herself, he could hold himself against her and wound her, to the point that she was left exhausted after Sasuke's intervention.

Sharingan
Shin possesses multiple fully-matured Sharingan implanted about his body. Because of his highly-adaptive body, Shin can maintain his Sharingan unhindered unlike most people not of Uchiha blood. At the same time, as all the Sharingan appear to be activated constantly, it can be assumed he has immense levels of chakra. With these eyes, he has heightened perception and is able to perform various complicated attack patterns. He also owns a mysterious creature with a Sharingan, and is able to share vision with it and others and can use his dōjutsu techniques through it as a medium.

With his right Sharingan, Shin is capable of using space–time ninjutsu, which he can create a barrier that instantaneously teleports himself and anything else within it to a location. Depending on the situation, he can manipulate the size and shape of the space affected.

Mangekyō Sharingan
Through unknown means, Shin was able to awaken the Mangekyō Sharingan in his right eye. Its pattern is a large circle around the pupil with three points. Uniquely, Shin's Mangekyō pattern is reflected in all of the Sharingan on his body, as well as the eyes of his clones and spying creature. Using his Mangekyō, Shin was able to telekinetically manipulate any tools after branding them with a special mark on his left hand. Shin demonstrated refined control, able to manipulate multiple weapons at once to attack his opponent from various angles as well as perform surgery on himself. He was likewise able to manipulate his multiple targets together in unison to form a myriad of shapes for further versatility in battle.

Medical Ninjutsu
As a medical-nin, Shin displays advanced knowledge of human anatomy and surgery. Favouring scalpels in combat, Shin commonly uses his Mangekyō Sharingan's technique to wield the tools telekinetically, expertly striking key points on the body to inhibit movement. He can also use the dōjutsu to perform surgery on himself, allowing him to replace his injured vital organs by transplanting healthy organs from his own clones.

Unique Body
Shin possesses a unique genetic make-up that will completely accept any new genetic material, be it tissue, organs or entire limbs, without a chance of rejection, allowing him to fully integrate it into his being. Doing so also allows Shin to make use of any genetic modification at its full potential. According to Orochimaru, it is this very trait that made it much easier for permanent and separate entity clones of him to be created. These clones are seemingly granted the same genetic modifications Shin, himself, underwent.

Shin also has great endurance, able to survive Sakura's chakra-enforced punch long enough to be treated with open surgery, which he performed himself while casually talking to the captured Sakura.

Naruto Gaiden: The Seventh Hokage and the Scarlet Spring
With the intent to eliminate the disgrace of the Uchiha clan, he tasks one of his clone to spy on Sasuke Uchiha. After his failed assassination, Shin returns to his father. After finding out that Sasuke's daughter, Sarada Uchiha, had left Konohagakure, he orders the clone to abduct her. Later after the Shin-clone returned following his failed abduction, Shin prepared to begin their next attack and called forth six Shin-clones, before teleporting with Shin to the Ridge Tower. The two arrived above Naruto and Sarada and attacked. After Naruto repelled the attack, Sasuke confronts the two.

Immediately, Sasuke faced off against Shin and repelled his blades. Before Sasuke could cut Shin with his sword, Shin caught and marked it. One of Shin's clones took the opportunity to attack from behind only to swap positions with Sasuke before he launched a fireball towards them. Without hesitation, Shin launches the clone in front of the fireball to shield himself from the flames. Applauding Sasuke's dōjutsu might, Shin announces his desire to make it his own and introduces himself. Having earlier marked Sasuke's sword, Shin manipulated the weapon and stabbed Naruto with it and launched another attack aimed at Sarada, only for Sasuke to shield her with his body. As Shin prepared another attack, Sakura Uchiha arrived and delivered a devastating blow in retribution for her family being attacked.

Badly injured and prime to be captured, Shin's spying creature came to his aid and teleported him, his clone and Sakura back to their base. Upon arriving, he struck down his burnt son. Afterwards, he prepared himself for surgery, ready to have his still alive son's organs transplanted into himself as Sakura watched. He revealed to Sakura that that was not his son but only his clone. Around him more clones of himself appeared. He told Sakura that they were supposed to act as 'Stock to be used as flesh'. He revealed that he was in fact one of Orochimaru's experiments. He tells Sakura that there is no reason to be sad because all living things eventually die. They then go on to argue about the ethics of using cloning for organ transplantation. Once completing his procedure, Shin firmly announced his desire to do away with inferior genetics and concepts of peace, to which Sakura decided to attack.

Shin quickly manipulated countless scalpels as a makeshift arm as he prepared to attack. He was, however, caught by surprised by Sasuke's timely arrival and crushed the wannabe-Uchiha's body with Susanoo. Realising he needed to retreat, Shin called for his clones to distract Sasuke and his allies. To Shin's horror, the clones instead stabbed him, plainly explaining that he is not needed any more. While the clones began battling against the Konoha-nin, Shin began to teleport and attempted to take the young girls with him through his creature warping them. Sarada, however, acted quickly and destroyed the creature while Shin succumbed to his injuries.

Trivia

 * means "new" in Japanese.
 * Despite being able to accept any genetic material, Shin says he specifically uses his clones for donor organs because they are "spare parts" and have the same DNA as him.

Quotes

 * "Peace means an end to evolution for humans, that's exactly what you all are."
 * "Species without evolution are eventually destroyed."