High school student Kaoru Uno lives a quiet life with his elderly grandmother, his only remaining family after the death of his parents. His world is turned upside down when he begins to see mysterious, malevolent creatures invisible to others. These beings are known as Shiryo or death spirits, monstrous entities that devour human souls. After his grandmother collapses due to a Shiryo attack, Kaoru is approached by the eccentric novelist Yoji Amane. Yoji reveals that he was a coworker of Kaoru’s late father and that his public career as a writer is just a front for his real job: a necromancer who fights Shiryo using controlled spirits. He also explains that a special ring left to Kaoru by his father is a tool for summoning his own personal Shiryo.

Rather than remain a protected civilian, Kaoru resolves to master his inherited powers to safeguard his grandmother himself and joins Yoji at the Amane Spiritual Medium Agency to be trained as a necromancer.

The story follows Kaoru as he learns to control his powerful Shiryo, a humanoid warrior named Shishi. Under Yoji’s eccentric mentorship, Kaoru begins the Necromancy Course Arc, where he trains with another expert named Midori to gain better command over his abilities. The central conflict escalates during the Ryu Arc. Kaoru is kidnapped by a powerful and deranged necromancer named Ryu. As Yoji and his allies, including a member of the Kyoen group, race to rescue him, Kaoru learns the tragic truth about his mother’s death and that his captor, Ryu (whose full name is Ryuji Amane), is actually Yoji’s older brother.

The narrative builds toward a final confrontation where Ryu’s ultimate goal is revealed: to revive Kaoru’s deceased mother. In the ensuing battle, Kaoru manages to master necromancy, but his soul is shattered. To save him, Yoji makes the ultimate sacrifice, offering up his brother Ryu to bring Kaoru back from the dead. The series concludes with Yoji faking his own death and retiring from the agency, leaving Kaoru to forge his own path in a world where the boundaries between the living and the dead remain dangerously thin.