The story follows Nanari Hel, a 12-year-old girl from a small village in the Kingdom of Doran, as she begins her six-year education at the prestigious magic academy on the floating "King's Island." Nanari's parents are an archaeologist and a demon slayer, respectively. Her dream is to become an attendant at the "Harre," a government office that handles demon slayer requests, inspired by a kind attendant she met as a child. Despite her parents' initial reservations about the demanding requirements for the role, Nanari excels in her village studies, aiming to be the best.
Upon arriving at the academy, Nanari is struck by the stark contrast between the noble students, adorned in elaborate dresses and suits, and her own simple attire. She finds herself in a classroom with a disproportionate number of nobles, leading to subtle mockery. She quickly develops a strong rivalry with Alwes Rockman, a handsome and seemingly arrogant noble who is her seatmate and consistently outranks her in academics and magic.
During her first year, Nanari discovers her magic type is Ice, a rare attribute, which causes her hair to turn a striking blue. This further isolates her from some students but also earns her the respect of her teachers, particularly for her determination. She forms close friendships with two other commoner girls, Nike and Benjamin, who share her ambition to "defeat the nobles" in academic and magical pursuits.
Over the next few years, Nanari diligently trains, aiming to surpass Rockman. She participates in various practical exams and competitions, often placing second to Rockman, fueling her competitive spirit. She also navigates the social dynamics of the academy, including the intense romantic pursuits of noble girls towards Rockman and Prince Zenon, and Benjamin's crush on a boy named Satanaus.
By her fifth year, Nanari has proven herself capable, even saving her friends during a challenging practical exam that involved rescuing companions from magical flames, despite her own injuries. She receives a recommendation letter to the Harre, a significant step towards her dream.
As graduation approaches in her sixth year, Nanari reflects on her time at the academy. She has grown significantly, both in magical ability and maturity. She has learned to accept her "second place" status to Rockman, acknowledging his consistent superiority while still striving for her own goals. The story culminates with the graduation ceremony and a final dance with Rockman, where he reveals a softer side and acknowledges their shared journey. Nanari, despite her lingering rivalry, feels a sense of accomplishment and looks forward to her future at the Harre, while Rockman is set to join the Royal Knights.
