Mushikaburi-hime follows Elianna Bernstein, the daughter of a baron in the Sauslind Kingdom and the latest heir to the Bernstein family's reputation as nobles who prize books above everything else. Her devotion to reading has earned her the nickname Bibliophile Princess instead of the simpler label of bookworm. Four years before the story begins, Crown Prince Christopher Selkirk Asherald offers her an unusual arrangement: if she agrees to become his fiancée, she will be free to spend her time reading and gain access to the royal archives, whose wide selection of books is more tempting to her than court society. Even though the role carries the responsibility of a great title, Elianna accepts.
Years later, Elianna still believes that the engagement was never meant to carry any romantic feeling. When she notices Christopher spending time with another girl, she assumes their agreement is nearing its end and that the quiet life she built around him will soon disappear. Instead, that uncertainty pushes both of them to confront the bond they have formed, opening a new chapter in their relationship as they come to understand each other and their genuine feelings more clearly.
