More than 40 years ago, unusual earthquakes occurred in many sea areas around the world.
The East China Sea, the North Atlantic, the South Pacific, the coast of Africa... Deep-sea fissures that had never existed before appeared on the seabed.
At first, they were attributed to a rare global crustal movement, until the rifts continued to deepen.
One day, human detection equipment can no longer reach their bottom.
In order to monitor these abnormal sea areas, humans have established strategic bases along the rifts.
The Seventh Coast is one of them.
Liu Yu is just an ordinary recycler here. Until an accident, a mecha returned from the deep sea severely damaged, and its central core lost in the sea had some unexplainable changes. A recycling mission brought Liu Yu truly close to the darkness for the first time...
