This is an era where humans and demons live together. However, one day the demon king and his army brought peace and wanted all dominion over the world. The demon king also kidnapped the princess of the human kingdom, Princess Syalis, and held her hostage. The incident sparked deep anger and sorrow for all of humanity. However, a teenager who is none other than a hero vows to save the princess and bring her home from the demon king's castle. On the other hand, while waiting for the hero to pick her up, the princess who had a strange hobby of sleeping was restless in the demon king castle, even though they didn't do anything to the princess, she couldn't sleep well. . with all the things that get in the way. Therefore, the princess must try herself and find various solutions to get the best quality sleep in her new castle.