In the first lunar month of 1853, Kasahara Ryōsaku sent a letter to Ōno to notify his colleagues of a man named Koyama Yōju, who was rumored to be conducting vaccinations in Ota village.

Kasahara sought to confirm two particularly worrisome points. First, had Ōno’s vaccinators shared any vaccines with that man? Second, did the man possess the necessary training to distinguish between true and false pocks? Kasahara reminded his colleagues of an “agreement from a previous year” that held them responsible for preventing unauthorized vaccinations within their domain. Although Kasahara signaled some understanding for his colleagues’ potential lapse of oversight—after all, this exclave was quite far away from the castle town—he professed to be “concerned for the sake of our profession.” By this, he probably meant that an ignorant and greedy vaccinator might undermine trust in the new treatment.

Kasahara was anxious not to offend his Ōno colleagues over what might have been a mere misunderstanding. He was much more explicit in his personal notes, which followed his copy of the letter. Kasahara had learned about Koyama from Naitō Dōitsu, a physician in Itō village, Sabae domain. Dōitsu’s father Teian had signed the vaccinators’ oath in 1850 as one of three physicians from Sabae domain. His home village Itō, which was somewhat removed from the central part of Sabae’s territory, shared a border with three of Nishikata’s villages (for locations, click on the pins on the map above). According to Naitō Dōitsu, Koyama Yōju had secretly stolen vaccine from him by “having a person come in contact with it,” probably by sending a child to Naitō to be vaccinated and then “tapping” the child for transmissions. Naitō said that when he confronted Koyama over the matter, the man apologized and asked for an official transmission. But when Naitō asked Kasahara for his opinion, the latter insisted that Koyama could only request to become part of the network if he brought his illegitimate vaccinations to a complete stop. Koyama’s reaction is unknown, but four years later, Ōno’s physicians suggested in a letter to Kasahara that when they investigated this rumor back in 1853, “nobody was conducting vaccinations any more at that time.”

It seems that Koyama had failed to gain access to the vaccinators’ network. He had flouted professional etiquette as well as domain borders. Yet in stealing the vaccine, he had traced the most convenient path the vaccine could take, namely between people living side by side within the same region, far away from the officially sanctioned clinics.

Ironically, two years later, in 1855, Naitō Dōitsu was himself accused of vaccinating villagers in an improper manner. According to a letter Kasahara wrote to Sabae's domain physicians, Naitō had gone around the countryside (including to Gamō village, which had been visited by Kasahara in 1854) and vaccinated children for money, using dried lymph he carried around with him in a box. Although the use of dried lymph was deemed less reliable, villagers reported that he did not bother to show up for follow-up visits to examine the children's reaction. Unlike Koyama, Naitō had actually assented to the vaccinators' oath, but had broken it by vaccinating outside the clinic, neglecting quality controls, and striving for monetary gain. Kasahara sent a letter to his colleagues in Sabae to ban Naitō from conducting further vaccinations. He even notified officials of Fukui domain (Kasahara, Hakushinki, 215-16).