Remnant Rock is a location in The Demon's Light. It is the sea-locked headquarters of Alchemilia Corporation, built on an island off the northern coast of Thales. Remnant Rock itself is completely inaccessible to civilians and most low-level employees. The island is first mentioned in "Bare Trees."
After Alchemilia Corporation was formed, the Arsene siblings began to expand from their home country in Nuyö to the Thelsh market. One of the many Alchemilia installations in the continent was an android factory built off the coast of what would become Port City. When the Great War caused the collapse of many corporations, Alchemilia was kept afloat with the production of androids at this facility. Numerous additions were made to the factory, creating a combination military base-research facility. After an experimental energy reactor was found to be a success, Alchemilia moved their headquarters from Gladea to Remnant Rock.
The island that houses Remnant Rock consists of a small mountain. Parts of the facility protrude from the mountain, and others are built outdoors in their entirety. A distinct blue-green steel alloy that can be found in Alchemilia products is used throughout the construction.
- A large bridge connects Remnant Rock to Port City's mainland. Built into its underside is a magnetic rail utilized by the Cetan, a levitation train that also attaches to each of Remnant Rock's primary sectors.
- The bridge connects to the lobby, where security androids verify employees' identities through iris and fingerprint recognition. A large elevator in the area leads upwards to the hangar, which is built into the island's cliffside and holds cargo and military aircraft.
- Beneath the elevator is the sub-aquatic reactor, which primarily provides the facility's energy. Numerous backup generators are located throughout Remnant Rock, offering a less-effective temporary fallback.
- The Genetics Sector is the deepest of Remnant Rock's scientific facilities. A majority of it is restricted to those with Gimel-tier security clearance due to the sensitive and unethical nature of the Genetics Department's work. The Pharmaceutical Department operates from a small installation in the Genetics Department.
- Remnant Rock's most spacious sector is the Robotics Sector, where androids are developed and mass-produced. The original facility on the island was a pre-war Alchemilia android factory.
- The Arms & Security Sector consists of both the production and design of Alchemilia weaponry, as well as the instruction of Alchemilia soldiers and commanders. It is attached to the dormitories, where Alchemilia soldiers and employees reside.
- The Detention Sector is the second-smallest of the sectors. It consists of a small prison of under one thousand inmates, overseen by a warden and a small company of Alchemilia soldiers equipped with mostly nonlethal riot-suppression weaponry.
- The smallest sector is the Administration Sector, which contains the offices and board-rooms of Alchemilia personnel, as well as the entire Communications Department. The offices of especially high-ranking employees are fitted with personal panic-rooms.