Mitsu's a window-washer in the Ring System, a civilization constructed after Earth was abandoned and turned into a nature preserve. His father died on the job five years earlier, and Mitsu takes his work seriously. Unfortunately, not all of his coworkers feel the same way, and they begin to resent the care and diligence he puts into clearing a vision of Earth for the residents of the Ring. One day, while staying late to check on his colleague's work, Mitsu loses radio contact. Will he meet the same fate as his father?