Kirin Kudo, a junior high school student, used to have a weak body. After drinking unicorn horn powder at the suggestion of his childhood friend Narumi Usagawa, he gained a stronger body than humans. Then one day, a boy named Satoru Togawa who calls himself a unicorn suddenly appears at Kirin's house in search of the horn that he lost long ago. However, other mythical beasts also followed the unicorn to the human world...