Fifth grader Wakaba can see things invisible beings other people can't. Because of this, she's bullied by her classmates and spends her days alone. But one day, she meets a strange pink creature who only says "Pupipo." It quickly becomes fond of Wakaba and protects her from evil beings. With its help, she befriends Reiko, a girl obsessed with the occult. Meanwhile, she meets Naoya, a boy who can also see invisible creatures, and decides to help him get rid of them.