Triple Gate Seal

The Triple Gate Seal (三門封印, Sanmon Fūin) is a powerful sealing technique developed and used by Samiya to seal Shukaku into Eika. Later, Eika understood the fundamentals of the seal through documents given to her by Samiya prior to her defection and has since ensured that the seal remains intact for her own benefit.

Usage
The Triple Gate Seal, as one might consider from its name, has three prominent uses. Upon inscribing the formula onto the host, the seal proceeds to absorb the entire quantity of its target and places it into the desired host. In order to do this, the chakra making up the sealed entity is distributed throughout the entire body and subsequently compressed into a density safe enough for it to be accessed without the host's body being corroded entirely. Nevertheless, this process isn't entirely guaranteed by the sealing itself, which means that the host naturally has to possess considerable quantities of chakra in order to be designated as the Jinchūriki. Furthermore, upon investigation of the seal, Eika realized these properties were associated with two of its spirals. The third spiral at the top was designated to altering the intensity of the seal, which would allow Eika to control how much power she was able to access of Shukaku's. By keeping this at a level where Shukaku's power was mixing with hers in a natural process, Eika's chakra was saturated with the enormous reserves of Shukaku over time without causing harmful side-effects to her body for the most part.

Effects
The effects of this seal are most evidently the successful sealing of Shukaku into Eika's body. Because she has been ingrained with Shukaku for almost all of her life, the seal has managed to stay especially strong, which has enabled Eika to converse with Shukaku on a level that has allowed their powers to synchronize, rather than Eika dominating Shukaku. In addition, the seal has shown to take the physical form of a three-segmented gate whenever Shukaku and Eika converse, making it quite safe for her to do so without risking her mental well-being.