On the matter of Öshio's alleged meeting with Zhou Yunshan (later, Feng Yunshan) in Nagasaki and their trip together to China, Ishizaki Tögoku notes: 'The problem here is the identity of Mr. Zhou, said to be a Chinese merchant, with whom Öshio and his son embarked on their journey. In the various works we have examined, I recall a work by Ökura Nagatsune, entitled Kiyö ki [Account of Nagasaki], which mentions this.' It is not clear what work this Kiyö ki refers to. I, for one, have never heard of such a work by Ökura, and after a brief examination of his writings, no work by this title comes to the fore. Nonetheless, Ishizaki quotes from it as follows:

Recently, a talented young Cantonese by the name of Zhou Yunshan came to Nagasaki. He is well-versed in both Dutch medical science and studies of the Yi jing (Classic of Changes). I gained considerably through a meeting with hirn, and if he were to wish to remain permanently on Japanese soil, I would make such a recommendation to the feudal lords. Last year Yunshan formed something called the Triads. He was arrested while spreading his [religious] message locally [in China] and by dressing up as a merchant escaped certain death. He now says that he has collected his books to take long-term refuge in Japan.