Eien

The is the name given to the collective of diseased shinobi, and other warriors, that were revived by Kaasage Tachinai to be his servants thanks to the Phantom Resurrection technique. As such the individual members of the Eien had no goals of their own and were simply puppets for the will of their summoner.

The Eien is comprised of a total of fifteen members, ten of which are the primary members, with another four being secondary members often times kept in reserve until Kaasage required them. The fifteenth member was Kaasage himself as its leader. Each member of the Eien was of some renown or possessed a special trait in order to pique Kaasage's interest as the average ninja were too common place for Kaasage's "ideal of perfection". While there was no set order of function for the group, they were commonly summoned in pairs, such as with Kōri Uōkā and Muon Yume which combined Kōri's skill with the Hidden Mist Technique and Muon's mastery of the Silent Killing technique. The full number of the Eien is almost never assembled in one place, as Kaasage mentioned that the high demand in chakra for him to keep them under his control makes it extremely dangerous and very short. His fight with Tenka Nihisaki was the first time in which he summoned all of them together in order to combat the Jinchūriki.

When not in use, each member of the Eien is stored within an underground cavern that rests beneath the village of Tsuri-mura. They group originated in Sunagakure, when Kaasage began researching on the bodies of the dead. While his motives were unclear, Kaasage successfully revived Seishoku Tetsu from death as the first member of his Eien before being found out by Sunagakure Ninja and forced to flee the village.

Members
All members are stated as active unless they are removed from Kaasage's control, in which case they are deceased.