"Radiant" is a fantasy action anime set in a world plagued by monstrous creatures known as Nemeses, which fall from the sky and infect humans with a curse. The story centers on Seth, a young sorcerer who survives a Nemesis attack and becomes infected, gaining the ability to wield magic. Unlike most infected individuals, Seth is determined to use his powers for good, aspiring to become a great sorcerer and find the mythical land of Radiant, the source of the Nemeses, to eradicate them permanently.

Seth trains under the guidance of Alma, a skilled sorcerer who becomes his mentor. Together, they embark on a journey to uncover the truth about Radiant and the origins of the Nemeses. Along the way, Seth encounters various allies and adversaries, including Doc, a quirky inventor, and Mélie, a fellow sorcerer with a dual personality. The group faces numerous challenges, including battles against powerful Nemeses, confrontations with the Inquisition—a militaristic organization that persecutes sorcerers—and internal struggles with their own fears and ambitions.

The narrative explores themes of prejudice, as sorcerers are often ostracized and feared by society due to their connection to the Nemeses. Seth’s journey is not only a physical quest but also a moral one, as he grapples with the ethical implications of his powers and the responsibility of protecting others. The story delves into the complexities of human nature, the consequences of hatred, and the pursuit of a better future.

As the series progresses, Seth uncovers deeper secrets about the world, including the true nature of the Nemeses and the Inquisition’s hidden agenda. The plot intertwines personal growth, political intrigue, and epic battles, creating a dynamic and engaging narrative. Seth’s unwavering determination and optimism serve as a driving force, inspiring those around him to challenge the status quo and strive for a world free from fear and oppression.