The Artificial-Tails (人工尾, Jinkōbi) is a peculiar phenemona. It's host is Gai Nagareboshi.
When the Sage of the Six Paths split up the Ten Tails into the Nine Tailed Beasts, a certain residue of that energy was left in the area that the Sage split the tailed beasts. This chakra, was then only compatible by somebody who had gained either the Rinnegan or Sharingan, had been in possession of high chakra levels and was able to access that area. This residue of chakra could was pulled out and fused with Gai Nagareboshi's own chakra, forming something similar to a Tailed Beast, having a state of existance similar to a tailed beast and it's own unique ability.
Activity inside GaiEdit
As the Artificial-Tails' jinchūriki, Gai is gifted with its enormous supply of chakra and stamina. It also gives Gai accelerated healing (recovering from minor injuries within a few seconds to major injuries within an hour, due to the legend which the mythological creature it is based of represents death and rebirth), and depending on the amount of the Artificial-Tails' chakra he's using, Gai is also given an increase in strength, speed, and his healing factor to impressive levels.