Shin

was a Konohagakure orphan who was recruited into the Root division of the village's Anbu.

Background
Even though he was trained to abandon his emotions, Shin grew close to a younger Root member, Sai. He recognised Sai's talent for art, and encouraged him to continue the hobby. Sai looked up to him as a brother and began to shed Root's teachings, but Shin soon died of an unknown disease, leaving Sai's training to suppress most of his memories of Shin. Prior to Shin's death, it was noted that he and Sai were supposed to fight to the death by Root regulations, in a final step to eradicate emotions. After Sai met Naruto Uzumaki, who he noted to be similar to Shin, Sai's memories of him returned, which brought a smile to his face.

In the anime, Sai and Shin were forced to fight to the death by Danzō Shimura to fully kill their emotions. Knowing that he was terminally ill and about to die at any minute, Shin told Sai to report to Danzō that he killed him in battle. Before telling him to go, Shin told Sai that he must suppress his feelings otherwise, the missions undertaken by Root would consume him. As Sai leaves to report to Danzō, Shin dies.

Personality
According to Sai, Shin and Naruto are very similar stating that Shin was also loud, impatient, and unrefined. Shin was also a very kind individual with a pleasant disposition as he helped Sai pursue his interest in drawing. He was also stated to be very tenacious and absent-minded.

Appearance
Shin had grey hair and light-coloured eyes, which are depicted as black in the anime. When he was a child, he wore a pale yellow shirt together with a pair of dark brown pants. These outfits were the ones he wore in the cover of Sai's picture book. When he was older, he wore the official uniform of the Anbu, and carried giant shuriken as well as a tantō on his back. After being reincarnated by Kabuto Yakushi, it was revealed that at some point before his death he used to wear an outfit exactly like the one his brother wears inclusive of the customary Root jacket. In the manga, he also wore a Konoha forehead protector when he was reincarnated.

Abilities
Shin was a very capable shinobi during his lifetime, enough to be reincarnated by Kabuto to fight in the Fourth Shinobi World War. He was shown to be skilled in kenjutsu, using the standard tantō of the Root shinobi to deliver swift slashes at the opponent. He was also capable of easily defeating multiple Anbu shadow clones using ordinary taijutsu.

Fourth Shinobi World War: Confrontation
In preparation for the Fourth Shinobi World War, Shin was reincarnated by Kabuto Yakushi to fight against the Allied Shinobi Forces. He was later assigned to the Surprise Attack and Diversion Platoon as the group's support.

After pursuing the three remaining members of the Infiltration and Reconnaissance Party atop Deidara's clay bird, he remained vigilant whilst Sasori manipulated the captive and booby-trapped Muta Aburame to attack the opposing Surprise Attack Division. Detecting that the enemy had evaded the blast, Shin tried to dive down to their position with tantō in hand, but was violently driven into the ground when Sai ambushed him from above. As his broken neck regenerated, he implored his brother to flee, remarking that Sai's team had no chance of victory against them. Briefly engaging Sai, Shin obstructed the enemy, after Omoi liberated Tokuma and Ranka. Confronted by Kankurō's Sasori puppet and Omoi, he avoided their attacks thanks to Sasori's assistance, before Hoheto Hyūga alerted his team to the fact that Shin's stomach was packed with explosive clay.

Just as he was about to be detonated, Shin was captured by Kankurō's Sanshōuo puppet, which effectively stifled the blast. As he reformed, he then told Sai that he didn't want to hurt him, as he had already been freed from Root. As an enraged Sai attacked Sasori and Deidara, Shin saw the image that Sai had drawn of the two together, recollecting the time when it was created. After the remainder of his platoon were restrained, Sai suggested they finish the fight they never got to start all those years ago but Shin tells him there was no need, as finally seeing Sai's drawing, had freed his soul. He then crumbled, leaving behind a pile of earth and ash along with the corpse of an unknown individual that was used as a sacrifice in the ritual.

Trivia

 * means "new".
 * In the anime, Shin's eyes were depicted as being black. However, when he was reincarnated — the only time his eyes are seen open in the manga — they are depicted as being light-coloured. Curiously, when Shin is reincarnated in the anime, his eyes are black in colour, however when Sasori uses Shin as a puppet, his eyes turn white as if his personality had been eliminated by Kabuto, which was not the case.
 * According to the databook(s):
 * His hobby was to look at pictures Sai drew.

Quotes

 * (To Sai) "I… don't want to harm you. In death… I was finally free of "Root"."
 * (To Sai) "I finally saw the drawing I'd always wanted to see… It looks like your drawing has freed my soul."