The setting is the Edo period. Ichitarou, the young master of Nagasakiya, one of the largest stores in Nihonbashi, has suffered from poor health since birth and is unable to go out. However, Ichitarou is always protected by demons such as Shirasawa and Inugami, who serve him. One night, Ichitarou goes out secretly and witnesses a murder. From that day on, bizarre murders begin to occur one after another in Edo... With the help of the demons, Ichitarou's search for the culprit begins!