NieA under 7 is a 13 episode anime series about Mayuko, a poor, introverted student who lives above a Japanese bathhouse, and NieA, a freeloading alien who lives in her closet and eats her food. The series begins with a light comedic tone (most of the early episodes are about schemes to rejuvenate the bathhouse), and becomes more serious later on, exploring the relationship between Mayuko and NieA, with an overall uplifting ending. It also touches lightly on discrimination and stereotypes: NieA is a sort of second-class citizen among aliens, and yells at anyone who calls her a 'stupid no-antenna' or similar. Another alien adopts sterotypical Indian dress and opens a covenience store.

NieA under 7 is based on a doujinshi by graphic designer Yoshitoshi ABe. NieA under 7's staff was made up of many people who worked on Serial Experiments Lain (director Takuya Sato was the storyboard artist for Lain, Yoshitoshi ABe was the character designer for Lain, etc...), and it is claimed that they chose to do this light-hearted series to cool off after the dark and psychological Serial Experiments Lain. This idea is further supported by the character Chiaki, a UFO fanatic who shares a name with Chiaki Konaka, the script writer for Lain.