When Aoi accidentally awakens a centuries-old Demon Lord, she finds herself tasked with keeping a glowing gem talisman on his forehead, a seal that seems to have a mind of its own. The problem? It slips off every time he gets flustered, causing magical chaos and endless headaches for Aoi. As she checks on him daily and navigates his silent, awkward affection, her feelings slowly begin to grow. But can a girl and a voiceless demon lord find love before the talisman decides to fall off one final time?