The world of Draw Your ARMS is plagued by mysterious swarms of nanomachines colloquially known as “micros.” Incidents involving the micros began occurring roughly three years ago, though their exact origin is unknown. Micros are known for their ability to “infect” both living organisms and inanimate objects, allowing them to dramatically manipulate their host. They seem to “crave” living things, however, and can only replicate while inside of a living host.

Whenever micros infect an inanimate object, however, said object can become what is known as an “Armored Rigging Micro System,” often shortened to “ARMS.” An ARMSystem seemingly “imprints” on whoever owns the original object, granting the owner a suit of biomechanical armor, imbuing them with heightened physical performance as well as unique abilities derived from the infected object.

ARMS are relatively uncommon, and it is unknown exactly what conditions lead to their creation, as they can not be recreated artificially at this time.