Despite being a cheerful and energetic eighth grader, Kaede struggles with shyness around boys. One day after school, she enters a mysterious shop and purchases a bright cocoa mug. Upon returning home and inspecting the bottom of the mug, she discovers an engraved note. The note states that if she reads it aloud while pouring hot cocoa into the mug, a love fairy or "muglox" will appear and grant her every wish. Though hesitant, Kaede follows the instructions and wishes to date Yuuki, the class heartthrob. Suddenly, a cute blue muglox named Mirumo appears, but he has no interest in helping Kaede, preferring to create mischief and indulge in chocolate instead.
As it turns out, Mirumo is the prince of the muglox world and has fled to avoid marrying Rirumu, his intended princess bride-to-be. However, Rirumu and other muglox, ranging from good to bad to downright crazy, set out to bring him back. This group of troublemakers disrupts the daily lives of Kaede and her friends, adding a new and exciting twist to their school days.
