Sankishin

The Sankishin (三輝神), also known as the Original Units (オリジナルユニット), are basis of all Arch-Enemy Event Weapons. Unlike the Arch-Enemies, the Original Units draw power directly from the Boundary. They are individually called the Amaterasu Unit, Susanoo Unit, and Tsukuyomi Unit, but details about them are unknown.

Amaterasu Unit
The Amaterasu Unit (アマテラスユニット), also known as the Master Unit, Amaterasu (マスターユニット・アマテラス) or simply the Master Unit (マスターユニット), is the top of the Original Units and it’s wielded by the Origin.

The Unit has the power of creation called the Izanagi system (イザナギシステム) – Izanami was born as its opposite and equal force. Wielder of this Unit is able to use Event Interferences on a massive scale.

It exists deep within the Boundary, and can be found only by the Successor of the Blue who holds the Power of the Eye.

As opposed to Takamagahara, which could only alter major phenomena (ones that may determine the fate of the world), the Amaterasu Unit can interfere and alter any event it chooses. Another difference between them is that the Master Unit cannot be Observed or acknowledged at all, with the Successor of the Blue being the sole exception. In a sense, it is closer to being a “God” than Takamagahara.

In AD 2200, Hades: Izanami, Relius Clover and Yūki Terumi tried to destroy it, so they used the Takamagahara system to create conflicts with Event Interferences. The girl rewound 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-13 assimilated 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 the Highlander: Takemikazuchi, but Rachel Alucard protected the Amaterasu Unit using her Tsukuyomi Unit.

While being in the Embryo, it was revealed that the Amaterasu Unit is empty because its wielder escaped. The girl’s body is crucified, she has stitches, and red and blue tubes are connected to her body.

Susanoo Unit
The Susanoo Unit (スサノオユニット), also known as the Time-Slaying Susanoo (刻斬りのスサノオ), is wielded by Hakumen, and originally by Yūki Terumi/Susanoo, before he forced himself to eject from it.

The Unit takes a form of an armored body itself, and it actually houses the user’s soul.

Currently, it only uses 20% of its original power. Its true purpose is to slash time without the risk of a paradox.

Susanoo, along with Tsukuyomi, exists to protect Amaterasu.

Hakumen is said to be the White Susanoo, while Terumi is the Black Susanoo.

It was first excavated by the Japanese Government from the First Area, 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 family. Rachel Alucard gave it to Jin Kisaragi, who then became Hakumen. It is bound to the Amaterasu Unit and its commands.

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:

At some point Terumi reclaimed the Susanoo Unit and became Susanoo once more until he was killed by Ragna and the others. After Terumi's death The Susanoo unit which still contains Hakumen's soul was sent into the boundary.

Tsukuyomi Unit
The Tsukuyomi Unit (ツクヨミユニット), also known as the Time-Protecting Tsukuyomi (刻護りのツクヨミ), is wielded by Rachel Alucard, who is the Successor of the Tsukuyomi Unit (ツクヨミユニットの継承者).

The Unit has tremendous defensive capabilities, also known as the “absolute defense” (絶対防御). Its true purpose is to protect time.

In AD 2199/12/31, after the timeloop was broken by the Calamity Trigger, Rachel uses the Tsukuyomi Unit to protect the 13th Hierarchical City of Kagutsuchi from the Highlander: Takemikazuchi’s destructive blast.

After the new year, in 2200/02, Rachel uses the Unit again, but on Ragna – she does it to protect him from dangers when he travels through the Boundary back to the Great Dark War. Thanks to this, the only damage he receives is a temporary amnesia.

Later, when Izanami attempts to destroy the Amaterasu Unit with Takemikazuchi’s blast, Rachel uses the Tsukuyomi Unit again, as her task as the Successor of the Tsukuyomi Unit is to protect the Master Unit.

Before Rachel can use the Unit, she has to activate it first with the following command: