Arche

Arche (アルケー, Arukē) is a type of nanomachine featured in Black★★Rock Shooter DAWN FALL and Black★★Rock Shooter BEFORE DAWN.

Description
Arche was conceived by the rogue Artemis to process human beings into a liquid metal as a resource to power kinetic bombardment from the moon. It also had other functions, such as acting as Lunatic's body and weapon, as well as the manufacture of Unmanned Forces' machines from Iron Oceans. It suspended in open atmosphere, forcing humans to wear respirators outdoor and purify surroundings indoor to minimize poisoning. Arche poisoning in human could lead to crystals forming within the blood. Some Unmanned Forces machines were also seen emitting Arche in purple mists, which were regarded as nanomachines in rampage and fatal to humans.

The Education Institution could also utilize Arche in a liquid metal form as a weapon, absorbing humans and other entities, including Strength's Gigantic Arm, upon contact.

Arche's effect on Hemiteos Units vary among individuals. Dismemberment wounds inflicted on Hermit, a Type 00 Hemiteos Unit, could not heal due to Arche's interference. Empress had a much higher tolerance against Arche while walking on shallow depths of Iron Ocean than Strength could.

Empress also had the ability to absorb Arche from the air and from fallen machines that were created with Arche, reprocess it, and use it to construct her own weapon called the coilgun. She could also manipulate it in the air to an extent, which was used once to save Norito and Miya from potential injuries and pull them towards her akin to telekinesis. The Arche emitted a blue glow when it came under Empress' effect.

History
Sometime after Artemis openly rebelled against mankind, it updated its avatar, Lunatic, and replaced her android body with one entirely represented by Arche. In this new form, Lunatic could dissipate and reform wherever Arche was present, as well as generating weapon and ammunition, which she used with great effect to defeat Hermit in a one-sided duel.

Following the Peacebuilding Forces and Hemiteos Units' defeat, Artemis spread Arche in open environment all over the world. Surviving humans had to wear respirators in the open, as well as to purify surroundings and resources indoor to minimize the risk of Arche poisoning. Iron Oceans also appeared where captured humans were processed by Arche into a liquid metal, with new Unmanned Forces machines manufactured from the same sites.

Etymology
Arche is derived from the Ancient Greek word ἀρχή (arkhḗ), which means "beginning" or "origin". In ancient Greek philosophy, Arche is the first principle, or underlying substance, of existing things.