Mayuko is living in a bath house and going to cram school until she can afford to pay her way to college. NieA is an alien living in her closet who likes to build UFO's in her room. Many years ago, an alien ship landed and it's inhabitants integrated into Japanese society. Mayuko has little money and almost no food while NieA is a freeloader. At school Mayuko meets an old classmate named Chiaki who wants to come to her house and see the UFO. Embarrassed about her bad living state and roommate, she is reluctant. Her feelings are confirmed when NieA launches her UFO right through the roof.

Needing to do something to help the bath house get back in the black, Mayuko, Nenji and NieA go to the crater in search of an oil that rumor has it exists there. Along the way, the group are attacked by giant plants and they lose their Bento lunches. When they return, they use the oil for the furnace and mix in some dead plants to cause a nice aroma. All is well until the plants start growing.

Mayuko is greeted by a large Indian man who seems to be a pervert. NieA recognizes him as the owner of a convenience store as an alien. He invites Mayuko there for their opening and then invites NieA to the alien meeting. NieA ends up going to the meeting with the promise of free Bento. The meeting ends up being between about five aliens with Chada being the most outspoken one of the group. Of course, this leads her and NieA to blows and the meeting comes to an end.

Mayuko has started a new job at a European restaurant where she delivers food (although she tells Chiaki that she's a waitress). After NieA has stuck Chada with a food bill at the restaurant she works at, Chada pays a visit to the restaurant. Mayuko runs a delivery when Genzo shows up looking for her so that he can give her some rice. When NieA come in, she and Chada start to fight again. What else can go wrong for Mayuko?

Still in the red, the Enohana Bath house must do something to bring in customers. When NieA waltzes in with several parts from a video game store that has closed down, Kotomi (the owner and manager of the bath house) has an idea on how to get more customers. They advertise a game day with the customers playing against the employees - the winner gets a year of free baths.