Cinder Tooth is a modern world highly consistent with real society. City life, medical care, transportation, policing, media, and ordinary people's lives all follow realistic logic, but an abnormal life erosion whose source has not yet been truly understood by humans is quietly entering this world. It can parasitize, pollute, and reconstruct the human body, causing the host to gradually break away from the original human structure and transform into a "Sui Lifeform" possessing strength, speed, recovery ability, and predatory instincts far exceeding ordinary people.