The main character, Richet, is a human girl who lives as a maid in the castle of the Lendia Empire, a country where demons live . She is the only human in a country where there are only demons. Richet, who was alone and feeling lonely, unexpectedly became friends with her imperial prince, Elhard. The two of them enjoy tea time together, go out to see the circus, and so on. Elhard was kind and caring for Richet, who didn't have any family or friends , but one day, everything changed. She learns a certain secret of Elhard. Knowing his secret, Richet tries to escape, but she is imprisoned by Elhard. He shows an unusual obsession . After her sweet training, Richet's thinking gradually dulled and she was turned into Elhard's obedient pet dog.