In Oval City, where robots are commonplace and used as tools by humans for most basic tasks, Iris Rain Umbrella is an android who lives a carefree and happy life caring for her master, Dr. Wendy von Umbrella, the head of robotics research at Oval University. According to Wendy, she created Iris to take the place of her younger sister, who lost her life in an accident, and whose name and likeness the house robot shares.

Iris does the work of a maid in the von Umbrella mansion—shopping, cooking, and cleaning—and wishes for these days to never end. However, this joyful existence is suddenly interrupted by a series of tragic events. Uprooted from her home, Iris must leave her comfortable life behind and adapt to her new circumstances if she wishes to survive.