Roy Revel is a frontier aristocrat from a lethargic small country who appears to be a listless and unmotivated student at the academy, earning him the nickname the fallen aristocrat. In truth, he is concealing an extraordinary secret: he is simultaneously the White Sword Saint Cloud, the revered patron god of the Kingdom of Albios, and the Black Grand Sage Eclipse, the equally celebrated guardian of the magical nation of Rutetia. By deliberately playing the role of a useless noble, Roy maintains a triple life, protecting his family and homeland while secretly manipulating the ongoing conflict against a powerful expansionist empire from the shadows. Despite his desire to retire from these duties, he must continue until a suitable successor emerges. His carefully constructed facade begins to fray when several talented and ambitious young women at the academy, each aspiring to become a sword saint or grand sage, take an interest in the outwardly mediocre student. Among them are Annette, a girl determined to master the magical arts and become a great sage; Enis Erlang, the student council president and top-ranked sword wielder at the academy, who harbors a peculiar personal secret as a coping mechanism for pressure; Cecilia, the first princess of the kingdom and a formidable wind-magic sword user, who propositions the Sword Saint for marriage; and Yukina, a promising candidate whom Roy begins training to eventually face Cecilia. As the empire launches large-scale invasions, deploying an elite guard unit and even magical puppets, Roy is forced to wield his full power as both sword saint and grand sage, confronting vast armies and powerful imperial agents. Later arcs see Roy dispatched to the trade nation of Venice alongside Annette, now a member of the Twelve Heavenly Magi, where they must rescue junior students and break an imperial naval siege while contending with the empire's youngest elite guard, Alexia. The escalating conflict eventually draws Roy, his allies from the academy, and the allied nations into an all-out assault on the imperial capital, where the emperor's true objectives, the secrets of the demon race, and a dire threat to Roy's beloved sister Lena come to light.