Niwa Makoto is a student who tolerates his aunt and other relatives’ company. His parents manage a business and don’t have enough time for a son. His life changed when he met a peer cousin Touwa Erio who acted like a freak. Touwa urges she is from another planet. She binds a mattress around her chest to contact with space. In fact, Erio once found herself in a sea. She was rescued but remembered nothing. Pizza was the only food she could eat with pleasure. Now she thinks it might be a mistake that she appeared on Earth. To discover her past, Touwa wanders in the suburbs with a mattress hoping to find another alien.