Information from source #2
This part has some small overlap from source #1, but I think it’s best to leave everything intact. This one seems to be quite different from the other sources that I have read, but it kinda fits with the other sources as well.
The Giant and the Dragon
On June 12th, 2003, a giant and dragon suddenly emerged in the skies of Shinjunku. The two fought an intense battle, and the giant fell at the end. Japan's Self Defense Force attacked the Red Dragon to avoid further catastrophe. People later found an unknown particle called Demonic Element, a source of the White Chlorination Syndrome. It was also recorded that a young man rode on the dragon's back, but this information cannot be verified.
White Chlorination Syndrome
People who developed the WCS either die or become killers who attack random people.
These berserk patients are later called “Legion”.
The Wall of Jericho
In order to stop the spreading of WCS, the Japanese government erected a wall around the Shinjuku area. The name is a reference to the to the Book of Joshua form the Bible.
Legion
WCS patients who manage to stay alive become extremely violent. Their bodies become much more powerful as their intelligence drop, and they attack anyone who has not contracted the WCS. The patients do not always retain their human form, and may
transform into monsters. WCS can be seen as the curse of a foreign God. Those who defy this god will die. Those who accepts this god will become Legion, and accept the mission to reduce the world to the nothing. This Foreign God is the God from Drakengard.
Red Eye
A Legion who is highly infected with the Demonic Element. The Red Eye is different from the normal Legion in that he is able to retain his intelligence, and can lead the army of Legion in their mission of ending the world. The Red Eye’s existence is comparable to Manah from Drakengard.
Multiple World Theory
By studying the remains of the Red Dragon, scientists have concluded that that there are multiple worlds. They have also found a mysterious particle named demonic element, and can develop magic from it.
Gestalt
By using magic, people have developed the technology to extract the soul from the body, and the name of the soul is called the Gestalt. While it is possible to evade the WCS by becoming a Gestalt, the Gestalt will slowly lose its intelligence and sense of self and become a corrupted being. It is only later that they have found a way to deal with this flaw. At the beginning only rich people can pay for Gestalt healing process.
Luciferase
A type of drugs used to treat the WCS. It cannot suppress the symptoms, but can at least delay its onset. The drug works the best with younger users. Most members of the Crusader use this drug.
Hemelin Organization
The Crusaders are a group that find and trains people who can fight the Legion. It was supposed to work with the Gestalt Project with the World Purifying Committee, but as more corporations become involved, the Crusaders have become more secretive.
State Weapons Laboratory (I am too tired to find the proper English name for this) In response to the founding of the Hemelin Organization, the Japanese government started the State Weapons Laboratory to strengthen its military power. Halua and Emil are magical weapons created by this organization.
Replicant System
By extracting data from humans who have undergone the Gestalt process, copies named Replicant (with no reproductive abilities) are created. To make it easier to manage the replicants, they are given an artificial personality. When the Gestalt and its corresponding Replicant combine, the original person would be restored. Replicant did not have a true sense of self at first, but they developed it after countless resurrections. The Black Scrawl is developed in the replicants because the data source (Gestalt) was already corrupted.
Project Gestalt
The World Purifying Committee’s true goal is to make every human go through the Gestalt process, and leaves the job of fighting the Legion to the replicants. When the WCS and legion problem is taken care of, the fusion of the Black and White books would transport the soul back into the replicant bodies.
Project Black Book
Part of the Gestalt Project. 13 Sealed Books are created through magic, with the Black Book and the White Book being two of them. The power from the fusion of the two books will forcefully return all Gestalts to their corresponding Replicant.
Corrupted Form
The corruption of Gestalt was a huge blow to Project Gestalt. The World Purifying Committee performed experiments on the masses in order to find the vaccine (demonic element). Nier and Yonah are two of the unlucky guinea pigs.
Every subject is given a copy of the Black Book. After Nier seeing the first person becoming a Gestalt, he quickly escaped with his sister. At the end, they are both forced to undergo the Gestalt process. While Gestalt Nier managed to retain his sense of self, the weaker Yonah experienced corruption immediately. In order to protect his sister, Nier accepted the World Purifying Committee’s proposal to become the Original Gestalt and supply demonic element to everyone. This allows his sister to be cryogenically frozen for a thousand years.
A thousand years later, Gestalt Nier/Shadow Lord realized that no advances were made, and choose to act on his own. At the same time, the occurrence of corruption has increased greatly, and the twins think that this is related to the actions of the Shadow Lord. Not being able to stop the Shadow Lord, they could only guide Replicant Nier to begin retrieving the Sealed Verses, and prematurely initiate the Project Black Book.
This series of mistakes seem to be created by one of the programmer. This programmer thinks that the Replicant should the true ruler of the world. (Don’t ask me where the hell this came from. I don’t know)