In a quiet area of Tokyo, a family of four was killed in their own home in broad daylight. The killer fled the crime scene, leaving behind a strange smell, somewhat similar to the smell of incense, and an eerie black sun painted on the ceiling with soot. The detective who began the investigation jumped into the river from the Rainbow Bridge. Inspector Kosuke Iwata and his slightly strange partner Noriko Sakai realize that they are up against a cold-blooded and calculating killer. They have every reason to believe that he does not intend to stop and the list of victims will soon be replenished. Coming events will show that their intuition did not deceive them...