TV-Series
Description
Eishi Sasazuka is a detective with the Tokyo Police Department. He initially investigates the death of Yako Katsuragi's father, subsequently granting her and the demon Neuro access to crime scenes, arresting suspects based on their discoveries, and managing case resolutions. Sasazuka presents as perpetually listless and emotionless, suffering from low blood pressure and requiring only 20 minutes of sleep per day. He subsists on minimal sustenance such as water, salt, and coffee, supplemented by sunlight, with suggestions he might undergo photosynthesis; his presence also lowers the surrounding temperature by about 3°C. Despite this demeanor, he possesses a sharp intellect and reacts with remarkable speed in crises. He is an exceptional marksman, always hitting his target with the first shot, and his combat skills exceed standard military training, allowing him to defeat multiple opponents single-handedly and construct complex deathtraps.

Over a decade prior, Sasazuka's entire family was murdered and dismembered to fit inside small boxes. Initially blamed on the serial killer X, the killings were later confirmed to be the work of Sicks, who targeted Sasazuka's father for uncovering sensitive information. This trauma caused Sasazuka to abandon his police academy exam and end his rivalry with classmate Naohiro Usui, who consequently developed resentment. Sasazuka vanished for years, operating within black market and guerrilla military circles to hunt his family's killer, acquiring unconventional combat abilities before rejoining the police force.

During investigations, Sasazuka becomes protective of Yako due to her resemblance to his deceased sister. He maintains a contentious relationship with Shinobu Godai, characterized by mutual dislike yet an underlying understanding. His partnership with officer Jun Ishigaki involves frequent destruction of Ishigaki's model collections. Colleague Shizuka Todoroki respects him but faces his criticism for excessive seriousness hindering investigations. Sasazuka grows increasingly suspicious of Neuro, witnessing the demon's use of 777 weapons and eventual revelation of his true form during a battle with the New Bloodline member Tierra, whom Sasazuka helps defeat.

Sasazuka's story concludes upon confirming Sicks as his family's killer. He abandons his duties, assaults underworld contacts for information, infiltrates Sicks' base after eliminating his subordinates, and confronts him. During this, X—disguised as Ishigaki—impales Sasazuka through the chest and torments him by shapeshifting into his dead family members. As Yako and Godai arrive but are separated by a barrier, Sasazuka offers Yako a final smile before Sicks executes him at point-blank range. His death triggers a department-wide campaign against the New Bloodline and leaves Yako burdened by guilt over her inability to intervene.