Zelda thought that living in a world overrun by zombies was bad enough, but she never expected anything worse than it, she was dodging a zombie and suddenly she found herself in a polluted wasteland world!Humans were divided into five classes, and she became the lowest citizen, also known as a "defective." In order to survive, Zelda has to become a cleaner in the 'cleaning center'. However, the "pollution" in this world was nothing like she had imagined. No one had ever told her that being a cleaner meant cleaning up monsters too!