Haruyoshi Kuga, a powerful exorcist in his original world, is betrayed and killed by his comrades due to his immense strength, which they perceive as a threat. Upon his death, he is reincarnated into a fantasy world where magic and monsters are commonplace. Retaining his memories and abilities from his previous life, Haruyoshi is reborn as Seika Lamprogue, the second son of a noble family. In this new world, he discovers that his exorcist techniques, which were considered obsolete in his former world, are highly effective against the supernatural threats here.

Seika’s reincarnation grants him access to a unique system of magic and spiritual energy, allowing him to harness his exorcist powers in ways that surpass the conventional magic of this world. Despite his young age, he quickly establishes himself as a formidable force, using his knowledge and skills to combat demons, spirits, and other malevolent entities. His abilities draw the attention of various factions, including the royal family, powerful mages, and rival nobles, all of whom seek to either recruit or eliminate him.

The narrative explores Seika’s journey as he navigates the political and social complexities of his new world while uncovering the mysteries of his reincarnation. He forms alliances with key figures, such as his loyal servant and childhood friend, Lian, and the skilled knight, Iris. Together, they face numerous challenges, including powerful adversaries, ancient curses, and the lingering shadows of Seika’s past life. The story balances action, strategy, and character development, as Seika strives to protect those he cares about while unraveling the deeper connections between his two lives. The series delves into themes of power, loyalty, and redemption, set against the backdrop of a richly detailed fantasy world.