In the late 20th century, global warming consumes 75% of the world habitable land, forcing mankind to build new, raised cities above those that are now claimed by the sea. But the flooding has not only claimed land. Millions of people have been killed as well, leaving humanities workforce severely depleted and as a result, have created a robotic workforce to handle the workload. To govern how this robotic workforce is treated, the UN creates the "New Geneva Convention", part of which is clause 21, which forbids robots that can pass as humans from being created, which are dubbed "hollow children" by the population. To enforce clause 21, the UN creates specialist R.U.S.T crews. When a hollow child breaks into the headquarters of robotics company Bergen, after discovering he is a hollow child and having lived his life believing himself to be human, the UN suspect the Amada corporation to be behind its creation. As a result, a R.U.S.T crew is dispatched to bring Amada's CEO before the UN security council to give answers.