Shin Uchiha

is a shinobi who was once Orochimaru's follower and also a test subject for genetic experimentation. He intends to revive the Akatsuki and return conflict to the world so that humans can once again evolve through it. Despite his surname he is not truly a member of the Uchiha clan.

Background
Shin was one of Orochimaru's experimental test subjects and followers, and possessed a unique genetic makeup 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 the secrets of genetics.

At some point Shin became intrigued by Itachi Uchiha and began to imitate the Uchiha Clan, 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, taking 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 the 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 for murdering Itachi and bringing shame to the Uchiha clan. He wishes to avenge Itachi by killing Sasuke, and wants to capture Sasuke's daughter, Sarada Uchiha, to use her in pursuit of his goals.

Appearance
Shin is a tall, pale, bald man with 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. 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 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's abilities are still largely unknown. However, given that he possesses multiple Sharingan, it can be reasoned that he is skilled in using the dōjutsu and its enhancements. Shin possesses a unique genetic makeup that will accept any genetic material without a chance of rejection, as well as create permanent clones of himself that become separate entities (unlike shadow clones).

Sharingan
Shin possesses multiple fully-matured Sharingan implanted into his head and left arm. Thus, it can be inferred that he is highly skilled with these eyes and has tremendous reserves of chakra, having them constantly activated while showing no signs of tiring. With them, he has heightened perception and is able to perform various complicated attack patterns. He also owns several mysterious creatures with Sharingan, and is able to share vision with it and others.

Mangekyō Sharingan
Through unknown means, Shin was able to awaken the Mangekyō Sharingan. Its pattern is a large circle around the pupil with three points spaced out, which is identical to his son and spying creature. The same Mangekyō pattern is also reflected on several Sharingan on top of his head. With his main right eye, he was shown to be able to telekinetically manipulate any tool he brands with a special mark. He is also able to perform a Space–Time Ninjutsu through the same eye and is able to use this ability through his creature as a medium.

Medical Ninjutsu
As a medical-nin, Shin displays advanced knowledge of human anatomy and surgery. Favouring scalpels in combat, Shin is able to use his Mangekyō Sharingan's unique dōjutsu 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.

Naruto Gaiden: The Seventh Hokage and the Scarlet Spring
With the intent to eliminate the disgrace of the Uchiha clan, he tasks his son Shin 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 his son to abduct her. Later after his son returned following his failed abduction, Shin prepared to begin their next attack and called forth his son and six copies of him, 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. Shin's son took the opportunity to attack from behind only to swap positions with Sasuke before he launched a fireball towards them. Without hesitation, Shin launches his son 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 Haruno 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 son 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.

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."