The story begins with the protagonist, Kamui, waking up injured and in pain after being severely bullied by classmates. He reflects on his life: his inability to use magic beyond basic household spells due to a severe lack of magical power, which led to his ostracization at the academy and his family's shame. His grandfather, an influential figure in the Honfreet family, despises him for this deficiency, treating him as a disgrace. Consequently, Kamui lives in a detached room and endures daily torment. Overwhelmed by despair, he contemplates suicide.
Suddenly, a person falls from the sky, landing near him. Kamui rushes to help, only to be met with hostility from the injured individual, who is revealed to be a demon. Despite the common perception of demons as cruel beings, Kamui feels no fear and even offers to be killed by the demon, as he was already contemplating death. The demon, initially dismissive and lecturing Kamui about the value of life, eventually agrees to kill him. However, as the demon prepares to strike, the sword glows, and Kamui is inexplicably impaled by it, experiencing an intense burning pain before losing consciousness.
Kamui awakens in a hospital, miraculously alive. He is questioned by a knight named Henry from the Royal Guard, who suspects Kamui is hiding something. Kamui confesses to being bullied, but omits the encounter with the demon. He is later disowned by his grandfather, the head of the Honfreet family, for his perceived incompetence and the shame he has brought upon them. Stripped of his family name and status, Kamui is forced to leave the Honfreet estate with only his father's belongings.
He finds refuge in an orphanage in the capital, where he encounters a kind couple, Viscount Kreuz and his wife, who are searching for an adopted heir for their frontier territory, a former demon territory. They are impressed by Kamui's intelligence and potential, especially his wife, Floria, who believes he possesses a unique magical aptitude. Kamui, initially hesitant due to his hatred of nobles, eventually agrees to become their adopted son, with the condition that some of his orphanage friends can accompany him. This decision is influenced by his mother's dying words and a growing sense of purpose.
Kamui, now Kamui Kreuz, enrolls in the Imperial Schutzlender Imperial Academy as a transfer student in the intermediate division. He is placed in Class E, a class composed mostly of commoners and students from less influential frontier territories, in contrast to the "Golden Generation" of students from powerful noble families who dominate other classes. Kamui's past experiences of bullying and his unique abilities, including a hidden talent for healing magic and a keen intellect, begin to shape his interactions within the academy.
During a sparring session, Kamui's hidden abilities are partially revealed when he is injured by a poisoned sword. He demonstrates a surprising proficiency in healing magic, baffling his classmates, particularly Claudia, a princess in disguise, and her loyal attendant Teresa. Kamui's past as a bullied commoner and his current noble status create a complex social dynamic.
Kamui and his friends, Lutz, Ignatz, Maria, and Alto, are revealed to be exceptionally talented individuals. Lutz excels in swordsmanship, while Ignatz and Maria show promise in magic. Alto, a strategic genius, becomes Kamui's trusted advisor. They form a pact to support Kamui, aiming to improve the lives of the common people and frontier territories, challenging the established noble hierarchy.
Kamui's interactions with other students, particularly Claudia and her rival Hildegard, reveal the political machinations within the academy and the wider empire. Hildegard, a powerful swordswoman from the Eastern Count family, and Deefleet, the second son of the Western Count family, are vying for influence. Kamui and his friends strategically navigate these power struggles, aiming to gain influence and protect their interests.
Kamui's past is further explored, revealing his mother, Sophia Honfreet, was a renowned "Light Saint" and a companion to a hero. His father's identity remains unknown, but his mother's legacy and the circumstances of his disownment by the Honfreet family are significant factors in his current path.
The narrative highlights the corruption within the empire and the church, as well as the systemic oppression of frontier territories. Kamui's journey is marked by his determination to forge his own path, protect his friends, and challenge the established order, all while grappling with his past and the weight of his mother's legacy.