The importation of the smallpox vaccine to Japan can be credited to physicians from two domains: Saga and Fukui. But conditions in these two domains differed. While Saga domain was a haven of Dutch Learning and a domain doctor, Narabayashi Sōken, took the lead in importing the vaccine, Dutch medicine in Fukui was far less developed and lacked support from the government. In Fukui, the initiative came from a single town doctor: Kasahara Ryōsaku (Hakuō, 1809-1880).

Unlike domain doctors, town doctors did not serve a lord nor were part of his retainer band; they practiced for and among commoners. In the 1840s, Hakuō was one of only a handful of physicians in his domain who had studied Dutch medicine. After learning about vaccinations from his teacher Hino Teisai in Kyoto, Hakuō tried in 1846 to propose importation through Nagasaki to the shogunate, which controlled foreign trade. But his domain government declined to forward the petition to the shogunate, possibly due to his low status. In 1848, Hakuō was finally granted permission. But before his delivery arrived from China, he got word that the vaccine had already reached Nagasaki from Batavia on a Dutch vessel on behalf of Saga domain and that Narabayashi Sōken had successfully vaccinated children in Nagasaki. The time was the 6th month of 1849.