In a previous life, a young woman who had just graduated as a librarian tragically lost her life in an earthquake while surrounded by the books that she loved so much. She was then reincarnated into the body of a 5-year-old girl named Maine in a fantasy world where she continues to cherish and live among her beloved books. Her ultimate goal is to lead a quiet, peaceful life surrounded by her collection. Although initially driven solely by her love for books, she soon found herself becoming more involved with other aspects of the world around her as she developed stronger feelings for her new family and those she encountered. Despite having a fragile body that left her easily fatigued and prone to strong fevers when pushed too hard, Maine possesses an exceptional talent for teaching others and inspiring them in their studies. While generally level-headed, she can become fiercely passionate about books, leading those around her to try to reason with her when she becomes too reckless. Over time, she has grown more receptive to the wisdom of those around her, especially as it comes from Ferdinand and Lutz.
She suffers from an illness knows as the "Devouring" which affects commoners born with mana, the more mana the worse the illness is. According to Ferd
At the end of Part 2, she becomes the daughter of Karstedt and her name gets changed to "Rozemyne."
As the daughter of Karstedt she is further adopted by archduke himself and becomes the daughter of the archduke.