Sankishin

The Sankishin (三輝神), also known as the Original Units (オリジナルユニット), they are the base for the Arch-Enemy Event Weapons. Unlike the Arch-Enemies, the Original Units draw power directly from the Boundary. This is mentioned in the Tsukuyomi Unit's chant, as well as being shown by the Susano'o Unit being unaffected by Celica's power, while the Amaterasu Unit was physically present within the Boundary itself.

Amaterasu Unit
The Amaterasu Unit (アマテラスユニット), also known as the Master Unit (マスターユニット), is the Original Unit that possesses the power of Event Interference. It is the top Unit of the Original Units. It is wielded by the Origin.

The Amaterasu Unit was located at the deepest part of the Boundary and could only be found by the Successor of the Blue who holds the power of the Eye of the Blue. Inside it "sleeps" a girl, and the world is made out of her dreams and memory through usage of Event Interference.

During BlazBlue: Chronophantasma, Hades: Izanami, Relius Clover and Yūki Terumi tried to destroy it, so they used the Takamagahara System to create conflicts with Event Interference. The girl rewinded time to eliminate those conflicts, but the more she did this, the "closer" she had to get. When she was close enough, Terumi had Nu -No. 13- synchronize with Noel Vermillion to draw the Amaterasu Unit from the Boundary using a Gate in the sky called Nemesis Horizon. Izanami tried to destroy it with Highlander: Takemikazuchi, but Rachel Alucard protected the Amaterasu Unit using her Tsukuyomi Unit. The both Units are still hovering in the sky over the 5th Hierarchical City of Ibukido.

According to Rachel, as opposed to the Takamagahara System, which could only alter major phenomena (ones that may determine the fate of the world), the Amaterasu Unit can intervene and alter any phenomenon it chooses. Another difference between them is that the Master Unit cannot be observed or acknowledged at all, with Successor of the Blue being the sole exception. In a sense, it is closer to being a "God" than the Takamagahara System.

In BlazBlue: Centralfiction it was revealed that the Amaterasu Unit is empty because its user escaped, and that Izanami is just the manifestation of its Drive. The girl's body is crucified, she has stitches, and red and blue tubes are connected to her body.

In XBlaze – Code: Embryo, the Master Unit was not called "Amaterasu Unit", and it is a sphere of blue light, called the Source of the Blue (蒼の根源).

Tsukuyomi Unit
The Tsukuyomi Unit (ツクヨミユニット), also known as Tsukuyomi the Time Guardian (刻護りのツクヨミ), is described as an ultimate defense. It is wielded by Rachel Alucard.

Rachel Alucard first used it to protect Kagutsuchi from Takemikazuchi's blast after Noel saved Ragna the Bloodedge from merging with Nu -No. 13-. She later put it on Ragna when he traveled through the Boundary, although he suffered temporary amnesia. When Izanami attempted to destroy the Amaterasu Unit, Rachel used Tsukuyomi to protect it.

The Tsukuyomi Unit's true purpose is to protect time.

Release command used by Rachel is:

Susano'o Unit
The Susano'o Unit (スサノヲユニット), also known as Susano'o the Time Cutter (刻斬りのスサノオ), is Hakumen's body itself. Currently, it only uses 20% of its original power. Its true purpose is to slash time without the risk of a paradox. It was originally owned by Yūki Terumi before he forced himself to eject from it. Despite no longer wielding the Susano'o Unit, Terumi seems to have its powers as a side effect. It was shown that the Unit actually houses the user's soul, not their entire body. Currently it's owned by Hakumen.

It was first excavated by the Japanese Government from the First Block, the same place from where the Black Beast appeared, and was immediately hidden so that nobody would know about it.

Yūki Terumi was going to give it to Relius Clover and Shūichirō Ayatsuki as research data toward the creation of Kusanagi, however it got picked by the Alucard Clan. Rachel Alucard gave it to Jin Kisaragi, who then became Hakumen. It is bound to the Amaterasu Unit and its commands.

Hakumen is the White Susano'o, while Terumi is the Black Susano'o.

While the unit itself is an empty vessel, it does seem to possess a will of its own, as in response to Jin's will to unify with it, the unit answered with:

Hakumen would later adapt those words into his battle chant.

It was later revealed in BlazBlue: Centralfiction that the Susano'o Unit is actually Terumi's original body and is the Japanese god of the same name. This explains why Terumi can still use its power even when separated from the armor.