God Tree

The was a tree revered in ancient times as a deity. It was said to bear a fruit of great power once in a millennium, although it was forbidden to consume the fruit. The circumstances under which the prohibition came to be are unknown. Consumption of the Shinju's fruit bestows an ability upon its consumer's body to produce chakra.

Background
Long before the founding of the hidden villages, during an era of endless wars between mankind, Kaguya Ōtsutsuki, a princess from a faraway land, came to the place of the conflict to end it. Having decided to bring peace, Kaguya breached the prohibition and ate the forbidden fruit of the Shinju, attaining god-like powers and making herself appear as a deity to mankind. Using her new-found power, Kaguya brought forth peace by force, causing her to be seen as a demon by some. Some time later, by means unknown, the Shinju incarnated together with Kaguya and took on the form which would come to be known as the Ten-Tails to claim the chakra of Kaguya's two sons. The Ten-Tails later rampaged the lands wanting the chakra, but the sons of Kaguya battled and sealed the Ten-Tails within Hagoromo, making him the first jinchuuriki. Later in Hagoromo's life, he separated the Ten-Tails' chakra into the nine tailed beasts, and sealed the husk of the Ten-Tails into the moon, subsequently sealing Kaguya and the Shinju for centuries. The Shinju never again existed as a single entity. After Madara Uchiha awakened the Rinnegan, he broke the seal, and brought forth the Ten-Tails' husk, planning to revive the Ten-Tails and insure the Eye of the Moon Plan.

Personality
The Shinju was an impartial entity, completely devoid of feelings and ideals as it stayed neutral and almost ambivalent to the constant wars that were waged around it by mankind.

Appearance
In its original form, the Shinju was a gargantuan tree.

Abilities
When Kaguya first cast the Infinite Tsukuyomi, she used the Shinju's roots to bind victims who were placed under said genjutsu, and the victims gradually reduced to shells of their former selves, ultimately becoming White Zetsu.

Effects of the Fruit
By consuming the fruit, Kaguya gained an enormous amount of chakra, said to be unrivaled to the point where she was able to stop the war-torn era she was in by herself, and was noted to be more powerful than the Sage of the Six Paths himself, with chakra that Naruto Uzumaki and Sasuke Uchiha described as being on an entirely different level from the Ten-Tails. With said amount of chakra, she was able to access a numerous amount of kekkei genkai such as the Byakugan, a red-coloured Rinnegan with Sharingan powers as a third eye on her forehead, which is able to cast the Infinite Tsukuyomi, as well as use Shikotsumyaku, and utilise the Truth-Seeking Ball -- a Kekkei Mōra -- and various other techniques. By utilising the Infinite Tsukuyomi and God: Nativity of a World of Trees, it is possible to regather the chakra of all living beings throughout the entire world, assimilating them into a single being once again, thus allowing the Shinju to grow a new in place of the one Kaguya once consumed.

Trivia

 * literally means 'god tree', and its size and nature have connections to both the world tree and the tree of life, motifs that are present in several real-life religions and mythologies throughout the world.
 * In addition, the story of the Shinju bearing the forbidden fruit is very similar to the story of the Tree of the knowledge of good and evil in Abrahamic religions, where Adam and Eve, the first humans, ate the forbidden fruit despite being told otherwise. Ultimately, while becoming wiser, it lead to their downfall by incurring the wrath of God. For disobeying Him, He forever cursed the two and their descendants. Adam's eldest son, Cain, would murder his younger brother, Abel, in anger and jealousy following God's rejection of his offering while accepting Abel's, which alludes to the struggle between the two sons of the Sage of the Six Paths.
 * The wooden dragon-like entities at the base of the Shinju may be a reference to Nidhogg, a dragon or serpent who eternally chews the roots of Yggdrasil in Norse mythology. Likewise with the appearance of the Shinju, it is said that should Nidhogg finally be free of its entrapment underneath Yggdrasil, its appearance into the world beyond its roots are said to herald the coming of Ragnarok, the end of the world and ultimate battle of the gods.
 * When the Ten-Tails was recreated into a tree by Obito in the Fourth Shinobi World War, it appeared as a tree, much like the Shinju, and was initially referred to as the Shinju by Gyūki, but it was later confirmed to be the Ten-Tails.
 * After the Demonic Statue of The Outer Path gained enough chakra from the nine tailed beasts, the Shinju lived on as the Ten-Tails in the Fourth Shinobi World War. The Ten-Tails was sealed within Obito Uchiha and later Madara Uchiha, the latter of which eventually was transformed into Kaguya Ōtsutsuki. After the fight with Kaguya, the Shinju, being one with her, was sealed by the Six Paths Chibaku Tensei in Kaguya's dimension.