Division 5-7-a or 5-7-abnormal is a highest ranking group within Hadean Forces and they're ONLY used for the Hollow research. 5-7-a is the only Division to undercome a different training from other Divisions, as well as modifying their DNA and/or biological bodies with Hollow traces and creatures that are believed to survive Hollow's conditions. These experiments were kept private until NS Aequoris was confident enough in 5-7-a's perfect state. Since the training and modification are quite costly and straining, there are no more than 10 members of the 5-7-a Division.

DOOMHOUNDS are megastructured machines designed to enter the Hollow or for transport on the ocean floor for longer periods of time. Measuring at 450 meter height and 350 meter lenght, they are able to carry 5 times their size. They are considered as portable bases for Hadean Forces, not only for carrying Divisions but also for transport of their resources and fuel to other underwater bases.
All DOOMHOUNDS are made of Hollow-enhanced metals, allowing them to walk in extreme ocean depths without implosion. There is currently 7 units used for transport and 5 units as mission-only.

For non-missions and casual transport, DOOMHOUNDS primarily use established routes in their navigation systems. While they're not piloted by anyone, there is a group of specialized technicians and pilots present on board at all times in case of emergencies. As of now, no emergencies were recorded.

URIELs are significantly smaller machines compared to DOOMHOUNDS, able to carry 2 pilots. They are fast paced, used for combat and exploration of the ocean floor. One of their main uses is defending DOOMHOUNDS' transport routes from deep water creatures (non-lethal) or from forces coming from other enterprises (lethal). URIELs are not equipped to enter the Hollow because of their size and different material.

Each Hadean Force Divison comes in even numbers, maximum of 20 - pilots are paired based on their compatibility with each other. A flock of URIELs is called MESSENGERS.