Detective Sagisaka Minoru, known as Sawada, operates from Shinjuku's Intervention Department. He investigates serial murders displaying supernatural evidence, specifically cases connected to mikura, predatory blood-draining yōkai. Sawada works these investigations alongside his partner, Narumi Kure. Unlike skeptical colleagues, he possesses an unwavering belief in the supernatural, rooted in personal experience. His daughter, Yoshiko, survived a mass murder she blamed on a mikura, resulting in her institutionalization within a psychiatric hospital. Sawada's core motivation is to vindicate Yoshiko and prove the truth of her claims, a purpose shaping his professional focus and actions.

During an investigation, Sawada and Kure meet Hinaru, a survivor of another mikura attack who embodies rural migrants seeking urban opportunities. Sawada's inquiry intensifies as mikura escalate assaults on hospitals, specifically targeting the injured karas agent, Otoha. These events culminate in citywide chaos when Eko, a former karas, attacks Tokyo with destructive metal tentacles. Seeking refuge, Sawada, Kure, Yoshiko, and Hinaru enter an emergency shelter commissioned by the chief of police.

The shelter transforms into a death trap when the police chief reveals himself as Ushi-oni, a yōkai preying on humans. During Ushi-oni's attack on Yoshiko, Sawada sacrifices himself by shielding her. This act enables Yoshiko's escape and fulfills his driving purpose to protect her. Sawada dies in the shelter amid the chaos, succumbing to Ushi-oni's assault.