Aliens have landed on Earth in the twenty-first century and are living among humans. Chigasaki Mayuko, a dirt-poor student, finds herself living with NieA, a low-caste ("Under Seven") alien, in peaceful Enohana. While Mayuko works hard to make ends meet, NieA appears to be careless about the repercussions of her behavior. The damaged alien mothership looms in the background as the unusual coupling emits the expected sparks...