Kidnapped by the Demon King and imprisoned in his castle, Princess Syalis is...bored. Winter has come, and Princess Syalis will do anything to stay warm, including creating a DIY magical device (known as a “Ko-tatsu”), knitting woolen underwear and trying to convince the castle blacksmith to make her a window to keep out the drafts. When she accidentally dies yet again—along with Stamper Cat—curious resurrection complications ensue. Then it’s Christmas and New Year’s! Who will the Demon King designate as naughty or nice? And will all of the other demons let poor Syalis join in any demon games...? And now the Demon King has insomnia!