"Radiant" is set in a world plagued by Nemeses, mysterious creatures that fall from the sky and bring destruction. These beings are impervious to conventional weapons, and only Sorcerers, individuals infected by a curse called Fantasia, can wield the magic necessary to combat them. However, Sorcerers are often ostracized and feared by society due to their cursed nature. The protagonist, Seth, is a young Sorcerer who dreams of becoming a hero and eradicating the Nemeses. After a Nemesis attack destroys his home, Seth embarks on a journey to find the mythical Radiant, the source of the Nemeses, with the hope of ending their threat once and for all.

Seth is accompanied by a diverse group of allies, including Doc, a skilled Sorcerer and mentor figure, and Mélie, a fellow Sorcerer with a dual personality and unique combat abilities. Together, they navigate a world filled with political intrigue, prejudice, and danger. The narrative explores themes of discrimination, as Sorcerers face persecution from the Inquisition, a powerful organization that views them as a threat to humanity. The Inquisition, led by figures like Commander Dragunov, seeks to control or eliminate Sorcerers, creating a tense dynamic between the two groups.

As Seth and his companions travel, they uncover deeper mysteries about the origins of the Nemeses and the true nature of Radiant. The story delves into the complexities of power, morality, and the consequences of wielding magic. Seth’s journey is marked by personal growth, as he grapples with his own limitations and the weight of his ambitions. The series balances action-packed battles with moments of introspection, highlighting the struggles of its characters as they confront both external enemies and internal conflicts.

The world-building in "Radiant" is expansive, featuring various factions, such as the Sorcerer Knights, who seek to protect humanity, and the Domitors, individuals who manipulate Nemeses for their own gain. The narrative also introduces a rich mythology surrounding the Nemeses and Radiant, gradually revealing their connection to the world’s history and the fate of its inhabitants. Through its exploration of these elements, "Radiant" presents a layered and engaging story that combines adventure, fantasy, and social commentary.