280 years after the signing of the "Third Armistice Agreement," due to the drastic reduction of surface living space, humanity began to develop underground. To solve the labor shortage, they created artificial lifeforms similar to humans called "Marigan." However, it has spiraled out of control, constantly expanding, multiplying, and turning the underground world into a veritable inferno. Its minions wreak havoc, retaliating against humanity and rebelling against it. When a human and "Marigan" investigation team infiltrated the underground city of "Capua" to investigate the truth behind the anomalies, they were attacked by a fanatical cult within "Marigan" and discovered their primal, almost obsessive, desire for human women. During numerous battles, the investigation team also discovered a spacetime rift called "Dimensional Distortion." Are these events related to "Marigan's" loss of control, or do the underground hold even more untold secrets?