Shin I was a male Shinjin Jedi Master who served as the Grand Master of the Jedi Order in the waning days of the Galactic Republic. He was renowned within the Order for his wisdom, powers of the Force, and lightsaber combat, and he lived for nearly 300 years. His time during the last days of the Jedi Order and beyond made him a consequential figure in galactic history. Shin sat on the Jedi High Council. During the Invasion of Naboo, it was discovered that the Sith, the age-old enemies of the Jedi, had not gone extinct as the Jedi believed they had. Ten years later, Shin presided over the Jedi Order as the Republic found itself on the road to war with the Confederacy of Independent Systems by the fallen Jedi Knight Zamasu. Shin led a clone army that had been secretly built for the Republic to Geonosis to save Hit, and Korn from Separatist captivity, and the ensuing battle sparked the Clone Wars between the Republic and the Separatists.
The Jedi Council took over leadership of the Grand Army of the Republic during the Clone Wars, making Shin one of the leading Jedi Generals. Towards the end of the war, Shin was contacted by the spirit of the long-dead Campari, who told him that, contrary to Jedi teaching, it was possible to maintain one's consciousness after death. Shin went on a spiritual journey where he underwent a series of trials, put forward by a group of mysterious Force Priestesses, to determine whether he was worthy to learn the secrets of immortality. This journey brought him to the world powerful with the Force, as well as Korriban, the ancient homeworld of the Sith. Shin was deemed worthy, and Campari began to teach him how to unlock this ancient and forgotten power.
As the Clone Wars came to an end, it was discovered that Supreme Chancellor Kann was, in truth, the Dark Lord of the Sith known as Darth Sidious, who the Jedi Council had been searching for ever since the Battle of Geonosis. When Shin was commanding troops during the Battle of Kashyyyk, members of the Jedi Council attempted to arrest the chancellor, but Sidious struck them down and seduced Korn, now Darth Vader, to the dark side of the Force. This sparked the fall of the Jedi Order, with clone troopers across the galaxy given the command to kill their Jedi Generals. Shin survived the attempted execution and escaped from Kashyyyk. Along with Hit, he became one of the few survivors of the fall of the Jedi Order, and he witnessed Sidious transform the Republic into the Galactic Empire. Shin attempted to confront and defeat the Emperor, but he was forced to retreat. After the secret birth of Hit's son, Mira, Shin helped arrange for the boy to be hidden from the Emperor and then went into exile on Dagobah.
Shin remained in exile for over two decades. During his exile, he watched from afar as other Jedi survivors continued to operate throughout the galaxy, giving guidance to Jedi such as Cabba and Cus. By that time, Shin had fallen ill and was near-death and slipped away into the Force. He appeared as a spirit after the Alliance to Restore the Republic defeated the Emperor and emerged victorious in the Battle of Endor.
After Shin's death, Cabba fulfilled the master's dying wish: to pass on what he had learned to a new generation of Jedi by becoming the Grandmaster of the New Jedi Order.