The job of baby-sittering monsters ... That is "Mamoribito"! A huge dragon that suddenly appeared 100 years ago and swallows the country. In search of the treasure that sleeps in it, people have begun to explore the body of the dragon, where the demons are slaughtered. Ariaris, a Heppoko Ranger who can't return to the ground from the dragon's body, lives in the body for a long time and is picked up by Lemon, who runs the "Mamoribito", to help the babysitter of the demons !? Rookie Mamoribito and her Ariaris babysitter x fantasy ...