Yami o Terasu Mono takes place at some undetermined point in the future in Vol City, a metropolis build around a volcano. One day, Ryuuga Dougai arrives in the city, drawn in by its high concentration of evil spirits known as Horrors, the ones plaguing Vol City being Madou Horrors. Ryuuga is, in fact, a Makai Knight and the latest knight to bear the title of Garo the Golden Knight. However, Garo's armor has mysteriously been tarnished black. Leaving many questions behind the loss of his golden armor's radiance, and the fate of his predecessor, Kouga Saezima. Ryuuga is the latest Garo The Golden Knight. He does not have any jurisdiction over any part of Japan, unlike his predecessor, and his habit of dressing in black clothes exudes a wild and imposing personality, while he is actually kind and positive. He possesses the innate ability to determine people's feelings by touching their belongings. Takeru Jakuzure is a fellow Makai Knight, serving as Zen the Flame Sword Knight, a self-styled playboy who would rather find a lady friend than battle Horrors. Aguri Kusugami is another Makai Knight, serving as Gai the Sky Bow Knight, the latest in a line of Makai Knights of the Kusugami clan, although he worries he cannot live up to the prestige his name carries. Rian is a beautiful and flashy Makai Priestess armed with the Makai Gun who always uses her skills for good, however, she has a hard time believing what others tell her due to her upbringing. Mado Ring Zaruba is the mentor and Madougu of the original Garo of the Saezima clan. He does not usually participate in fights but does give advice. However, Zaruba rarely speaks while he is with Ryuuga. Burai is a Makai Priest based in Vol City who is Aguri's partner and Rian's mentor. He uses a Makai Beast named Ragou in combat. He seems to have some history with Ryuuga. ~ Enhou is the female commander of the special forces task force SG1. She is not sure of the significance of the appearances of Horrors in Vol City, but she suspects Ryuuga to be behind it somehow.