In a world where demon is alive, magical girls take quest to defeat demon king until world become peace again. Hazuki Yuu is a high school boy that short and cute make people adore him. Many people including his self don't know that he actually vessel where Demon King was sealed.
After 10 years of search, a female demon finally found him in human world. She make investigation and going same school as Hazuki just to getting closer and try undo the seal.

Follow the story of cute shota boy in his daily life when demon after him.