The goddess Venus, jealous of the beautiful human girl Psyche, blames Psyche’s pet unicorn, Unico, for the good luck that keeps her safe from Venus’s cruel intentions. Unico possesses an amazing power to make everyone he meets happy, though it is unclear whether this comes from his personality or the powers of his horn. Angered, Venus banishes Unico, and the West Wind begins transporting him from one place and time to another. In a heavily polluted city, Unico meets a sickly girl named Chiko, whose health has been ruined by the pollution of a nearby factory that darkens the sky. Determined to cheer her up, cure her, and destroy the factory, Unico sets out to protect her.