In the realm of Ars, humanity wages a prolonged battle against colossal beasts pillaging the land and draining its riches. At the forefront of this fight stand the nagimori, revered champions who harness the volatile might of kannagi—entities brimming with untamed magic. Amidst grieving his fallen comrade, ex-nagimori Jiiro encounters Kuumi, a fledgling wielder of mystical abilities. Bound by a pact forged in crisis to repel a monstrous incursion, Jiiro unearths Kuumi's dark past: a fugitive from a sinister lab pursued by Mezami's lackeys, the overseer of a shadowy research institute. Sworn to aid Kuumi in her flight from relentless pursuers, Jiiro embarks on a journey with his enigmatic ally and the enigmatic Myaa, a companion adorned with a feline guise. As the trio traverses the landscapes of Ars, machinations of powerful figures unfurl, revealing a chilling truth—the true monsters may not lurk in the wilderness, but within the hearts of men.