The Giant, also known as the queen-beast, is an antagonist from Cavia's earlier game Drakengard who, along with the protagonist and the Dragon, ends up in the modern day Tokyo in the game's branch E and also starts the background of NieR RepliCant and NieR Gestalt. After her defeat, her corpse dissolved into "maso", otherworldly particles that caused the White Chlorination Syndrome, whereas the particles of the Red Dragon were used as the basis for the development of magic.
The contraction of WCS causes a pact to be formed between the infected human and the God of another world. If the human rejects the pact, their entire composition will change to salt, killing them. If the pact is accepted, they are turned into mindless, violent monsters known as Legions.