Ground Control to Psychoelectric Girl

The story follows high school boy Niwa Makoto, who lives with his aunt's family while his parents are away for work. There, he meets his enigmatic cousin Touwa Erio, a girl his age who wraps herself in a futon and claims to be an alien. She survives mostly on pizza. Erio had disappeared for six months before being found floating in the sea. Though she remembers nothing from that time, she believes an alien was involved and now drifts around town still wrapped in her futon.