The Nishikata exclave was located in Niu County, about 30 kilometers away from Ōno domain's castle town in the hill country between Echizen’s lowland corridor and the Sea of Japan. Two of its twelve villages bordered directly on the coast. In 1850, Ōno domain established a rural intendant’s (daikan) office in Nishikata because the exclave had become increasingly important for the domain’s responsibilities in coastal defense. The intendant’s office was placed in the fief’s main village—Ota, a rural center with about 1,000 residents.

It is unclear whether and when Ōno’s vaccinators attempted to bring the vaccine to Nishikata, but their colleagues in the vaccinators’ societies of Fukui and other towns certainly deemed them responsible for vaccination-related matters within the exclave. Kasahara Hakuō had two separate exchanges with Ōno's domain physicians Nakamura Taisuke and Hayashi Unkei that clarified his expectations regarding Nishikata. The first of these exchanges dates to 1853.