Katina, the daughter of a baron, was born with a good ear. She is especially sensitive to people's voices, and once she hears someone's voice, she never forgets it and can distinguish it accurately. Although her good hearing sometimes caused her problems, Katina quietly an obediently studied hard and was chosen to be the princess's personal attendant because of her excellent grades. Thanks to this, she was not very good at socializing, and compared to her beautiful older sister, she was the plain and inconspicuous younger sister. On the other hand, her fiancé, who was chosen while she was still in school, is the son of a count and the princess's guardian knight. He has a face so beautiful that women envy him, and although he is a diligent and talented knight, he is a very quiet man. It has been half a year since their engagement, and although she has never spoken to him, the first time she heard his voice, it was irresistible to Katina! This is a story about how the two of them grew closer from the first time they exchanged words, and how Katina, who was plain and inconspicuous, gradually began to shine.