"Kagirohi - Shaku Kei" is a supernatural thriller set in a world where ancient rituals and modern society intersect. The narrative centers on Shaku Kei, a young man who inherits a mysterious artifact known as the Kagirohi, a relic tied to an ancient clan with the power to manipulate time and space. The artifact binds him to a centuries-old conflict between two factions: the Kagirohi Clan, who seek to preserve balance in the world, and the Kurohana, a rogue group determined to exploit the artifact's power for their own gain.

Shaku Kei, initially unaware of the artifact's significance, is thrust into this hidden war after a series of violent encounters with Kurohana operatives. As he learns to harness the Kagirohi's abilities, he discovers that the artifact is sentient and communicates with him through cryptic visions and dreams. These visions reveal fragments of a forgotten history, including the tragic fate of the Kagirohi Clan and the true purpose of the artifact. Alongside him is Rin, a skilled warrior and the last surviving member of the Kagirohi Clan, who becomes his mentor and protector. Rin's knowledge of the artifact and its history proves crucial as they navigate the escalating conflict.

The story unfolds through a series of episodic battles and investigations, as Shaku Kei and Rin confront Kurohana agents, each of whom wields unique supernatural abilities tied to their own artifacts. The Kurohana's leader, Akatsuki, is a formidable antagonist driven by a personal vendetta against the Kagirohi Clan, seeking to rewrite history to erase their legacy. As the stakes rise, Shaku Kei must grapple with the moral implications of wielding the Kagirohi's power, particularly as it begins to take a toll on his physical and mental well-being.

The narrative explores themes of legacy, sacrifice, and the consequences of tampering with time. Flashbacks and visions provide insight into the Kagirohi Clan's past, revealing how their downfall was orchestrated by betrayal and ambition. These revelations deepen the connection between Shaku Kei and Rin, as they uncover shared ties to the clan's history. The series builds toward a climactic confrontation between Shaku Kei and Akatsuki, where the true nature of the Kagirohi's power and its role in maintaining the world's balance is fully revealed. The resolution leaves lingering questions about the cost of preserving order and the enduring influence of the past on the present.