Ichitarō is the young master of Nagasakiya, one of the largest commercial stores in Edo's Nihonbashi district. Frail and sickly since birth, his poor health confines him indoors, isolating him from a typical life, yet his nature remains kind-hearted.

His secluded existence is perpetually guarded by a devoted group of supernatural beings, including spirits and demons such as Shirasawa, an Inugami, Sasuke, and Jinkichi.

One night, he secretly ventures beyond his home and directly witnesses a murder. This event triggers a series of bizarre killings throughout Edo. Driven to uncover the culprit, he embarks on an investigation, aided consistently by his supernatural companions.